This patch adds the core parts of KMSAN runtime and associated files:
- include/linux/kmsan-checks.h: user API to poison/unpoison/check memory
- include/linux/kmsan.h: declarations of KMSAN memory hooks to be
referenced outside KMSAN runtime
- lib/Kconfig.kmsan: declarations for CONFIG_KMSAN and CONFIG_TEST_KMSAN
- mm/kmsan/Makefile: boilerplate Makefile
- mm/kmsan/kmsan.h: internal KMSAN declarations
- mm/kmsan/kmsan.c: core functions that operate with shadow and
origin memory and perform checks, utility functions
- mm/kmsan/kmsan_init.c: KMSAN initialization routines
- scripts/Makefile.kmsan: CFLAGS_KMSAN
The patch also adds the necessary bookkeeping bits to struct page and
struct task_struct:
- each struct page now contains pointers to two struct pages holding
KMSAN metadata (shadow and origins) for the original struct page;
- each task_struct contains a struct kmsan_task_state used to track
the metadata of function parameters and return values for that task.
Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx>
To: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Wolfram Sang <wsa@xxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
---
v2:
- dropped kmsan_handle_vprintk()
- use locking for single kmsan_pr_err() calls
- don't try to understand we're inside printk()
v3:
- fix an endless loop in __msan_poison_alloca()
- implement kmsan_handle_dma()
- dropped kmsan_handle_i2c_transfer()
- fixed compilation with UNWINDER_ORC
- dropped assembly hooks for system calls
v4:
- splitted away some runtime parts to ease the review process
- fix a lot of comments by Marco Elver and Andrey Konovalov:
-- clean up headers and #defines, remove debugging code
-- dropped kmsan_pr_* macros, fixed reporting code
-- removed TODOs
-- simplified kmsan_get_shadow_origin_ptr()
- actually filter out IRQ frames using filter_irq_stacks()
- simplify kmsan_get_metadata()
- include build_bug.h into kmsan-checks.h
- don't instrument KMSAN files with stackprotector
- squashed "kmsan: add KMSAN bits to struct page and struct
task_struct" into this patch as requested by Marco Elver
v5:
- s/kmsan_softirq/kmsan_context everywhere (spotted by kbuild test
robot <lkp@xxxxxxxxx>)
Change-Id: I4b3a7aba6d5804afac4f5f7274cadf8675b6e119
---
arch/x86/Kconfig | 1 +
include/linux/kmsan-checks.h | 127 ++++++++
include/linux/kmsan.h | 335 +++++++++++++++++++++
include/linux/mm_types.h | 9 +
include/linux/sched.h | 5 +
lib/Kconfig.debug | 2 +
lib/Kconfig.kmsan | 22 ++
mm/kmsan/Makefile | 11 +
mm/kmsan/kmsan.c | 547 +++++++++++++++++++++++++++++++++++
mm/kmsan/kmsan.h | 161 +++++++++++
mm/kmsan/kmsan_init.c | 79 +++++
mm/kmsan/kmsan_report.c | 143 +++++++++
mm/kmsan/kmsan_shadow.c | 456 +++++++++++++++++++++++++++++
mm/kmsan/kmsan_shadow.h | 30 ++
scripts/Makefile.kmsan | 12 +
15 files changed, 1940 insertions(+)
create mode 100644 include/linux/kmsan-checks.h
create mode 100644 include/linux/kmsan.h
create mode 100644 lib/Kconfig.kmsan
create mode 100644 mm/kmsan/Makefile
create mode 100644 mm/kmsan/kmsan.c
create mode 100644 mm/kmsan/kmsan.h
create mode 100644 mm/kmsan/kmsan_init.c
create mode 100644 mm/kmsan/kmsan_report.c
create mode 100644 mm/kmsan/kmsan_shadow.c
create mode 100644 mm/kmsan/kmsan_shadow.h
create mode 100644 scripts/Makefile.kmsan
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 8d298164dda2a..376c13480def2 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -140,6 +140,7 @@ config X86
select HAVE_ARCH_KASAN if X86_64
select HAVE_ARCH_KASAN_VMALLOC if X86_64
select HAVE_ARCH_KCSAN if X86_64
+ select HAVE_ARCH_KMSAN if X86_64
select HAVE_ARCH_KGDB
select HAVE_ARCH_MMAP_RND_BITS if MMU
select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
diff --git a/include/linux/kmsan-checks.h b/include/linux/kmsan-checks.h
new file mode 100644
index 0000000000000..2e4b8001e8d96
--- /dev/null
+++ b/include/linux/kmsan-checks.h
@@ -0,0 +1,127 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * KMSAN checks to be used for one-off annotations in subsystems.
+ *
+ * Copyright (C) 2017-2019 Google LLC
+ * Author: Alexander Potapenko <glider@xxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#ifndef _LINUX_KMSAN_CHECKS_H
+#define _LINUX_KMSAN_CHECKS_H
+
+#include <linux/build_bug.h>
+#include <linux/types.h>
+
+#ifdef CONFIG_KMSAN
+
+/*
+ * Helper functions that mark the return value initialized.
+ * Note that Clang ignores the inline attribute in the cases when a no_sanitize
+ * function is called from an instrumented one. For the same reason these
+ * functions may not be declared __always_inline - in that case they dissolve in
+ * the callers and KMSAN won't be able to notice they should not be
+ * instrumented.
+ */
+
+__no_sanitize_memory
+static inline u8 KMSAN_INIT_1(u8 value)
+{
+ return value;
+}
+
+__no_sanitize_memory
+static inline u16 KMSAN_INIT_2(u16 value)
+{
+ return value;
+}
+
+__no_sanitize_memory
+static inline u32 KMSAN_INIT_4(u32 value)
+{
+ return value;
+}
+
+__no_sanitize_memory
+static inline u64 KMSAN_INIT_8(u64 value)
+{
+ return value;
+}
+
+/**
+ * KMSAN_INIT_VALUE - Make the value initialized.
+ * @val: 1-, 2-, 4- or 8-byte integer that may be treated as uninitialized by
+ * KMSAN's.
+ *
+ * Return: value of @val that KMSAN treats as initialized.
+ */
+#define KMSAN_INIT_VALUE(val) \
+ ({ \
+ typeof(val) __ret; \
+ switch (sizeof(val)) { \
+ case 1: \
+ *(u8 *)&__ret = KMSAN_INIT_1((u8)val); \
+ break; \
+ case 2: \
+ *(u16 *)&__ret = KMSAN_INIT_2((u16)val);\
+ break; \
+ case 4: \
+ *(u32 *)&__ret = KMSAN_INIT_4((u32)val);\
+ break; \
+ case 8: \
+ *(u64 *)&__ret = KMSAN_INIT_8((u64)val);\
+ break; \
+ default: \
+ BUILD_BUG_ON(1); \
+ } \
+ __ret; \
+ }) /**/
+
+/**
+ * kmsan_poison_shadow() - Mark the memory range as uninitialized.
+ * @address: address to start with.
+ * @size: size of buffer to poison.
+ * @flags: GFP flags for allocations done by this function.
+ *
+ * Until other data is written to this range, KMSAN will treat it as
+ * uninitialized. Error reports for this memory will reference the call site of
+ * kmsan_poison_shadow() as origin.
+ */
+void kmsan_poison_shadow(const void *address, size_t size, gfp_t flags);
+
+/**
+ * kmsan_unpoison_shadow() - Mark the memory range as initialized.
+ * @address: address to start with.
+ * @size: size of buffer to unpoison.
+ *
+ * Until other data is written to this range, KMSAN will treat it as
+ * initialized.
+ */
+void kmsan_unpoison_shadow(const void *address, size_t size);
+
+/**
+ * kmsan_check_memory() - Check the memory range for being initialized.
+ * @address: address to start with.
+ * @size: size of buffer to check.
+ *
+ * If any piece of the given range is marked as uninitialized, KMSAN will report
+ * an error.
+ */
+void kmsan_check_memory(const void *address, size_t size);
+
+#else
+
+#define KMSAN_INIT_VALUE(value) (value)
+
+static inline void kmsan_poison_shadow(const void *address, size_t size,
+ gfp_t flags) {}
+static inline void kmsan_unpoison_shadow(const void *address, size_t size) {}
+static inline void kmsan_check_memory(const void *address, size_t size) {}
+
+#endif
+
+#endif /* _LINUX_KMSAN_CHECKS_H */
diff --git a/include/linux/kmsan.h b/include/linux/kmsan.h
new file mode 100644
index 0000000000000..071e75f426f7a
--- /dev/null
+++ b/include/linux/kmsan.h
@@ -0,0 +1,335 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * KMSAN API for subsystems.
+ *
+ * Copyright (C) 2017-2019 Google LLC
+ * Author: Alexander Potapenko <glider@xxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+#ifndef LINUX_KMSAN_H
+#define LINUX_KMSAN_H
+
+#include <linux/dma-direction.h>
+#include <linux/gfp.h>
+#include <linux/stackdepot.h>
+#include <linux/types.h>
+#include <linux/vmalloc.h>
+
+struct page;
+struct kmem_cache;
+struct task_struct;
+struct sk_buff;
+struct urb;
+
+#ifdef CONFIG_KMSAN
+
+/* These constants are defined in the MSan LLVM instrumentation pass. */
+#define KMSAN_RETVAL_SIZE 800
+#define KMSAN_PARAM_SIZE 800
+#define KMSAN_PARAM_ARRAY_SIZE (KMSAN_PARAM_SIZE / sizeof(depot_stack_handle_t))
+
+struct kmsan_context_state {
+ char param_tls[KMSAN_PARAM_SIZE];
+ char retval_tls[KMSAN_RETVAL_SIZE];
+ char va_arg_tls[KMSAN_PARAM_SIZE];
+ char va_arg_origin_tls[KMSAN_PARAM_SIZE];
+ u64 va_arg_overflow_size_tls;
+ depot_stack_handle_t param_origin_tls[KMSAN_PARAM_ARRAY_SIZE];
+ depot_stack_handle_t retval_origin_tls;
+ depot_stack_handle_t origin_tls;
+};
+
+#undef KMSAN_PARAM_ARRAY_SIZE
+#undef KMSAN_PARAM_SIZE
+#undef KMSAN_RETVAL_SIZE
+
+struct kmsan_task_state {
+ bool allow_reporting;
+ struct kmsan_context_state cstate;
+};
+
+/**
+ * kmsan_initialize_shadow() - Initialize KMSAN shadow at boot time.
+ *
+ * Allocate and initialize KMSAN metadata for early allocations.
+ */
+void __init kmsan_initialize_shadow(void);
+
+/**
+ * kmsan_initialize() - Initialize KMSAN state and enable KMSAN.
+ */
+void __init kmsan_initialize(void);
+
+/**
+ * kmsan_task_create() - Initialize KMSAN state for the task.
+ * @task: task to initialize.
+ */
+void kmsan_task_create(struct task_struct *task);
+
+/**
+ * kmsan_task_exit() - Notify KMSAN that a task has exited.
+ * @task: task about to finish.
+ */
+void kmsan_task_exit(struct task_struct *task);
+
+/**
+ * kmsan_alloc_page() - Notify KMSAN about an alloc_pages() call.
+ * @page: struct page pointer returned by alloc_pages().
+ * @order: order of allocated struct page.
+ * @flags: GFP flags used by alloc_pages()
+ *
+ * Return:
+ * * 0 - Ok
+ * * -ENOMEM - allocation failure
+ *
+ * KMSAN allocates metadata (shadow and origin pages) for @page and marks
+ * 1<<@order pages starting at @page as uninitialized, unless @flags contain
+ * __GFP_ZERO.
+ */
+int kmsan_alloc_page(struct page *page, unsigned int order, gfp_t flags);
+
+/**
+ * kmsan_free_page() - Notify KMSAN about a free_pages() call.
+ * @page: struct page pointer passed to free_pages().
+ * @order: order of deallocated struct page.
+ *
+ * KMSAN deallocates the metadata pages for the given struct page.
+ */
+void kmsan_free_page(struct page *page, unsigned int order);
+
+/**
+ * kmsan_split_page() - Notify KMSAN about a split_page() call.
+ * @page: struct page pointer passed to split_page().
+ * @order: order of split struct page.
+ *
+ * KMSAN splits the metadata pages for the given struct page, so that they
+ * can be deallocated separately.
+ */
+void kmsan_split_page(struct page *page, unsigned int order);
+
+/**
+ * kmsan_copy_page_meta() - Copy KMSAN metadata between two pages.
+ * @dst: destination page.
+ * @src: source page.
+ *
+ * KMSAN copies the contents of metadata pages for @src into the metadata pages
+ * for @dst. If @dst has no associated metadata pages, nothing happens.
+ * If @src has no associated metadata pages, @dst metadata pages are unpoisoned.
+ */
+void kmsan_copy_page_meta(struct page *dst, struct page *src);
+
+/**
+ * kmsan_gup_pgd_range() - Notify KMSAN about a gup_pgd_range() call.
+ * @pages: array of struct page pointers.
+ * @nr: array size.
+ *
+ * gup_pgd_range() creates new pages, some of which may belong to the userspace
+ * memory. In that case these pages should be initialized.
+ */
+void kmsan_gup_pgd_range(struct page **pages, int nr);
+
+/**
+ * kmsan_slab_alloc() - Notify KMSAN about a slab allocation.
+ * @s: slab cache the object belongs to.
+ * @object: object pointer.
+ * @flags: GFP flags passed to the allocator.
+ *
+ * Depending on cache flags and GFP flags, KMSAN sets up the metadata of the
+ * newly created object, marking it initialized or uninitialized.
+ */
+void kmsan_slab_alloc(struct kmem_cache *s, void *object, gfp_t flags);
+
+/**
+ * kmsan_slab_free() - Notify KMSAN about a slab deallocation.
+ * @s: slab cache the object belongs to.
+ * @object: object pointer.
+ *
+ * KMSAN marks the freed object as uninitialized.
+ */
+void kmsan_slab_free(struct kmem_cache *s, void *object);
+
+/**
+ * kmsan_kmalloc_large() - Notify KMSAN about a large slab allocation.
+ * @ptr: object pointer.
+ * @size: object size.
+ * @flags: GFP flags passed to the allocator.
+ *
+ * Similar to kmsan_slab_alloc(), but for large allocations.
+ */
+void kmsan_kmalloc_large(const void *ptr, size_t size, gfp_t flags);
+
+/**
+ * kmsan_kfree_large() - Notify KMSAN about a large slab deallocation.
+ * @ptr: object pointer.
+ *
+ * Similar to kmsan_slab_free(), but for large allocations.
+ */
+void kmsan_kfree_large(const void *ptr);
+
+/**
+ * kmsan_vmap_page_range_noflush() - Notify KMSAN about a vmap.
+ * @start: start address of vmapped range.
+ * @end: end address of vmapped range.
+ * @prot: page protection flags used for vmap.
+ * @pages: array of pages.
+ *
+ * KMSAN maps shadow and origin pages of @pages into contiguous ranges in
+ * vmalloc metadata address range.
+ */
+void kmsan_vmap_page_range_noflush(unsigned long start, unsigned long end,
+ pgprot_t prot, struct page **pages);
+
+/**
+ * kmsan_vunmap_page_range() - Notify KMSAN about a vunmap.
+ * @addr: start address of vunmapped range.
+ * @end: end address of vunmapped range.
+ *
+ * KMSAN unmaps the contiguous metadata ranges created by
+ * kmsan_vmap_page_range_noflush().
+ */
+void kmsan_vunmap_page_range(unsigned long addr, unsigned long end);
+
+/**
+ * kmsan_ioremap_page_range() - Notify KMSAN about a ioremap_page_range() call.
+ * @addr: range start.
+ * @end: range end.
+ * @phys_addr: physical range start.
+ * @prot: page protection flags used for ioremap_page_range().
+ *
+ * KMSAN creates new metadata pages for the physical pages mapped into the
+ * virtual memory.
+ */
+void kmsan_ioremap_page_range(unsigned long addr, unsigned long end,
+ phys_addr_t phys_addr, pgprot_t prot);
+
+/**
+ * kmsan_iounmap_page_range() - Notify KMSAN about a iounmap_page_range() call.
+ * @start: range start.
+ * @end: range end.
+ *
+ * KMSAN unmaps the metadata pages for the given range and, unlike for
+ * vunmap_page_range(), also deallocates them.
+ */
+void kmsan_iounmap_page_range(unsigned long start, unsigned long end);
+
+/**
+ * kmsan_context_enter() - Notify KMSAN about a context entry.
+ *
+ * This function should be called whenever the kernel leaves the current task
+ * and enters an IRQ, softirq or NMI context. KMSAN will switch the task state
+ * to a per-thread storage.
+ */
+void kmsan_context_enter(void);
+
+/**
+ * kmsan_context_exit() - Notify KMSAN about a context exit.
+ *
+ * This function should be called when the kernel leaves the previously entered
+ * context.
+ */
+void kmsan_context_exit(void);
+
+/**
+ * kmsan_copy_to_user() - Notify KMSAN about a data transfer to userspace.
+ * @to: destination address in the userspace.
+ * @from: source address in the kernel.
+ * @to_copy: number of bytes to copy.
+ * @left: number of bytes not copied.
+ *
+ * If this is a real userspace data transfer, KMSAN checks the bytes that were
+ * actually copied to ensure there was no information leak. If @to belongs to
+ * the kernel space (which is possible for compat syscalls), KMSAN just copies
+ * the metadata.
+ */
+void kmsan_copy_to_user(const void *to, const void *from, size_t to_copy,
+ size_t left);
+
+/**
+ * kmsan_check_skb() - Check an sk_buff for being initialized.
+ *
+ * KMSAN checks the memory belonging to a socket buffer and reports an error if
+ * contains uninitialized values.
+ */
+void kmsan_check_skb(const struct sk_buff *skb);
+
+/**
+ * kmsan_handle_dma() - Handle a DMA data transfer.
+ * @address: buffer address.
+ * @size: buffer size.
+ * @direction: one of possible dma_data_direction values.
+ *
+ * Depending on @direction, KMSAN:
+ * * checks the buffer, if it is copied to device;
+ * * initializes the buffer, if it is copied from device;
+ * * does both, if this is a DMA_BIDIRECTIONAL transfer.
+ */
+void kmsan_handle_dma(const void *address, size_t size,
+ enum dma_data_direction direction);
+
+/**
+ * kmsan_handle_urb() - Handle a USB data transfer.
+ * @urb: struct urb pointer.
+ * @is_out: data transfer direction (true means output to hardware)
+ *
+ * If @is_out is true, KMSAN checks the transfer buffer of @urb. Otherwise,
+ * KMSAN initializes the transfer buffer.
+ */
+void kmsan_handle_urb(const struct urb *urb, bool is_out);
+
+#else
+
+static inline void __init kmsan_initialize_shadow(void) { }
+static inline void __init kmsan_initialize(void) { }
+
+static inline void kmsan_task_create(struct task_struct *task) {}
+static inline void kmsan_task_exit(struct task_struct *task) {}
+
+static inline int kmsan_alloc_page(struct page *page, unsigned int order,
+ gfp_t flags)
+{
+ return 0;
+}
+static inline void kmsan_free_page(struct page *page, unsigned int order) {}
+static inline void kmsan_split_page(struct page *page, unsigned int order) {}
+static inline void kmsan_copy_page_meta(struct page *dst, struct page *src) {}
+static inline void kmsan_gup_pgd_range(struct page **pages, int nr) {}
+
+static inline void kmsan_slab_alloc(struct kmem_cache *s, void *object,
+ gfp_t flags) {}
+static inline void kmsan_slab_free(struct kmem_cache *s, void *object) {}
+static inline void kmsan_kmalloc_large(const void *ptr, size_t size,
+ gfp_t flags) {}
+static inline void kmsan_kfree_large(const void *ptr) {}
+
+static inline void kmsan_vmap_page_range_noflush(unsigned long start,
+ unsigned long end,
+ pgprot_t prot,
+ struct page **pages) {}
+static inline void kmsan_vunmap_page_range(unsigned long start,
+ unsigned long end) {}
+
+static inline void kmsan_ioremap_page_range(unsigned long start,
+ unsigned long end,
+ phys_addr_t phys_addr,
+ pgprot_t prot) {}
+static inline void kmsan_iounmap_page_range(unsigned long start,
+ unsigned long end) {}
+
+static inline void kmsan_context_enter(void) {}
+static inline void kmsan_context_exit(void) {}
+
+static inline void kmsan_copy_to_user(
+ const void *to, const void *from, size_t to_copy, size_t left) {}
+
+static inline void kmsan_check_skb(const struct sk_buff *skb) {}
+static inline void kmsan_handle_dma(const void *address, size_t size,
+ enum dma_data_direction direction) {}
+static inline void kmsan_handle_urb(const struct urb *urb, bool is_out) {}
+
+#endif
+
+#endif /* LINUX_KMSAN_H */
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 4aba6c0c2ba80..ba8d5808259bc 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -216,6 +216,15 @@ struct page {
not kmapped, ie. highmem) */
#endif /* WANT_PAGE_VIRTUAL */
+#ifdef CONFIG_KMSAN
+ /*
+ * Bits in struct page are scarce, so the LSB in *shadow is used to
+ * indicate whether the page should be ignored by KMSAN or not.
+ */
+ struct page *shadow;
+ struct page *origin;
+#endif
+
#ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
int _last_cpupid;
#endif
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 983389c3c26d1..208bff758b9cd 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -15,6 +15,7 @@
#include <linux/sem.h>
#include <linux/shm.h>
#include <linux/kcov.h>
+#include <linux/kmsan.h>
#include <linux/mutex.h>
#include <linux/plist.h>
#include <linux/hrtimer.h>
@@ -1199,6 +1200,10 @@ struct task_struct {
struct kcsan_ctx kcsan_ctx;
#endif
+#ifdef CONFIG_KMSAN
+ struct kmsan_task_state kmsan;
+#endif
+
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
/* Index of current stored address in ret_stack: */
int curr_ret_stack;
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 9f6e6edbd9949..e6f251b83437e 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -823,6 +823,8 @@ config DEBUG_STACKOVERFLOW
source "lib/Kconfig.kasan"
+source "lib/Kconfig.kmsan"
+
endmenu # "Memory Debugging"
config DEBUG_SHIRQ
diff --git a/lib/Kconfig.kmsan b/lib/Kconfig.kmsan
new file mode 100644
index 0000000000000..187dddfcf2201
--- /dev/null
+++ b/lib/Kconfig.kmsan
@@ -0,0 +1,22 @@
+config HAVE_ARCH_KMSAN
+ bool
+
+if HAVE_ARCH_KMSAN
+
+config KMSAN
+ bool "KMSAN: detector of uninitialized memory use"
+ depends on SLUB && !KASAN
+ select STACKDEPOT
+ help
+ KMSAN is a dynamic detector of uses of uninitialized memory in the
+ kernel. It is based on compiler instrumentation provided by Clang
+ and thus requires Clang 10.0.0+ to build.
+
+config TEST_KMSAN
+ tristate "Module for testing KMSAN for bug detection"
+ depends on m && KMSAN
+ help
+ Test module that can trigger various uses of uninitialized memory
+ detectable by KMSAN.
+
+endif
diff --git a/mm/kmsan/Makefile b/mm/kmsan/Makefile
new file mode 100644
index 0000000000000..a9778eb8a46a1
--- /dev/null
+++ b/mm/kmsan/Makefile
@@ -0,0 +1,11 @@
+obj-y := kmsan.o kmsan_instr.o kmsan_init.o kmsan_entry.o kmsan_hooks.o kmsan_report.o kmsan_shadow.o
+
+# KMSAN runtime functions may enable UACCESS checks, so build them without
+# stackprotector to avoid objtool warnings.
+CFLAGS_kmsan_instr.o := $(call cc-option, -fno-stack-protector)
+CFLAGS_kmsan_shadow.o := $(call cc-option, -fno-stack-protector)
+CFLAGS_kmsan_hooks.o := $(call cc-option, -fno-stack-protector)
+
+KMSAN_SANITIZE := n
+KCOV_INSTRUMENT := n
+UBSAN_SANITIZE := n
diff --git a/mm/kmsan/kmsan.c b/mm/kmsan/kmsan.c
new file mode 100644
index 0000000000000..037f8b5f33a57
--- /dev/null
+++ b/mm/kmsan/kmsan.c
@@ -0,0 +1,547 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KMSAN runtime library.
+ *
+ * Copyright (C) 2017-2019 Google LLC
+ * Author: Alexander Potapenko <glider@xxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <asm/page.h>
+#include <linux/compiler.h>
+#include <linux/export.h>
+#include <linux/highmem.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/kmsan.h>
+#include <linux/memory.h>
+#include <linux/mm.h>
+#include <linux/mm_types.h>
+#include <linux/mmzone.h>
+#include <linux/percpu-defs.h>
+#include <linux/preempt.h>
+#include <linux/slab.h>
+#include <linux/stackdepot.h>
+#include <linux/stacktrace.h>
+#include <linux/types.h>
+#include <linux/vmalloc.h>
+
+#include "../slab.h"
+#include "kmsan.h"
+
+#define KMSAN_STACK_DEPTH 64
+#define MAX_CHAIN_DEPTH 7
+
+/*
+ * Some kernel asm() calls mention the non-existing |__force_order| variable
+ * in the asm constraints to preserve the order of accesses to control
+ * registers. KMSAN turns those mentions into actual memory accesses, therefore
+ * the variable is now required to link the kernel.
+ */
+unsigned long __force_order;
+EXPORT_SYMBOL(__force_order);
+
+bool kmsan_ready;
+/*
+ * According to Documentation/x86/kernel-stacks, kernel code can run on the
+ * following stacks:
+ * - regular task stack - when executing the task code
+ * - interrupt stack - when handling external hardware interrupts and softirqs
+ * - NMI stack
+ * 0 is for regular interrupts, 1 for softirqs, 2 for NMI.
+ * Because interrupts may nest, trying to use a new context for every new
+ * interrupt.
+ */
+/* [0] for dummy per-CPU context. */
+DEFINE_PER_CPU(struct kmsan_context_state[KMSAN_NESTED_CONTEXT_MAX],
+ kmsan_percpu_cstate);
+/* 0 for task context, |i>0| for kmsan_context_state[i]. */
+DEFINE_PER_CPU(int, kmsan_context_level);
+DEFINE_PER_CPU(int, kmsan_in_runtime_cnt);
+
+struct kmsan_context_state *kmsan_task_context_state(void)
+{
+ int cpu = smp_processor_id();
+ int level = this_cpu_read(kmsan_context_level);
+ struct kmsan_context_state *ret;
+
+ if (!kmsan_ready || kmsan_in_runtime()) {
+ ret = &per_cpu(kmsan_percpu_cstate[0], cpu);
+ __memset(ret, 0, sizeof(struct kmsan_context_state));
+ return ret;
+ }
+
+ if (!level)
+ ret = ¤t->kmsan.cstate;
+ else
+ ret = &per_cpu(kmsan_percpu_cstate[level], cpu);
+ return ret;
+}
+
+void kmsan_internal_task_create(struct task_struct *task)
+{
+ struct kmsan_task_state *state = &task->kmsan;
+
+ __memset(state, 0, sizeof(struct kmsan_task_state));
+ state->allow_reporting = true;
+}
+
+void kmsan_internal_memset_shadow(void *addr, int b, size_t size,
+ bool checked)
+{
+ void *shadow_start;
+ u64 page_offset, address = (u64)addr;
+ size_t to_fill;
+
+ BUG_ON(!metadata_is_contiguous(addr, size, META_SHADOW));
+ while (size) {
+ page_offset = address % PAGE_SIZE;
+ to_fill = min(PAGE_SIZE - page_offset, (u64)size);
+ shadow_start = kmsan_get_metadata((void *)address, to_fill,
+ META_SHADOW);
+ if (!shadow_start) {
+ if (checked)
+ panic("%s: not memsetting %d bytes starting at %px, because the shadow is NULL\n",
+ __func__, to_fill, address);
+ /* Otherwise just move on. */
+ } else {
+ __memset(shadow_start, b, to_fill);
+ }
+ address += to_fill;
+ size -= to_fill;
+ }
+}
+
+void kmsan_internal_poison_shadow(void *address, size_t size,
+ gfp_t flags, unsigned int poison_flags)
+{
+ bool checked = poison_flags & KMSAN_POISON_CHECK;
+ depot_stack_handle_t handle;
+ u32 extra_bits = kmsan_extra_bits(/*depth*/0,
+ poison_flags & KMSAN_POISON_FREE);
+
+ kmsan_internal_memset_shadow(address, -1, size, checked);
+ handle = kmsan_save_stack_with_flags(flags, extra_bits);
+ kmsan_set_origin_checked(address, size, handle, checked);
+}
+
+void kmsan_internal_unpoison_shadow(void *address, size_t size, bool checked)
+{
+ kmsan_internal_memset_shadow(address, 0, size, checked);
+ kmsan_set_origin_checked(address, size, 0, checked);
+}
+
+depot_stack_handle_t kmsan_save_stack_with_flags(gfp_t flags,
+ unsigned int reserved)
+{
+ depot_stack_handle_t handle;
+ unsigned long entries[KMSAN_STACK_DEPTH];
+ unsigned int nr_entries;
+
+ nr_entries = stack_trace_save(entries, KMSAN_STACK_DEPTH, 0);
+ nr_entries = filter_irq_stacks(entries, nr_entries);
+
+ /* Don't sleep (see might_sleep_if() in __alloc_pages_nodemask()). */
+ flags &= ~__GFP_DIRECT_RECLAIM;
+
+ handle = stack_depot_save(entries, nr_entries, flags);
+ return set_dsh_extra_bits(handle, reserved);
+}
+
+/*
+ * Depending on the value of is_memmove, this serves as both a memcpy and a
+ * memmove implementation.
+ *
+ * As with the regular memmove, do the following:
+ * - if src and dst don't overlap, use memcpy();
+ * - if src and dst overlap:
+ * - if src > dst, use memcpy();
+ * - if src < dst, use reverse-memcpy.
+ * Why this is correct:
+ * - problems may arise if for some part of the overlapping region we
+ * overwrite its shadow with a new value before copying it somewhere.
+ * But there's a 1:1 mapping between the kernel memory and its shadow,
+ * therefore if this doesn't happen with the kernel memory it can't happen
+ * with the shadow.
+ */
+static void kmsan_memcpy_memmove_metadata(void *dst, void *src, size_t n,
+ bool is_memmove)
+{
+ void *shadow_src, *shadow_dst;
+ depot_stack_handle_t *origin_src, *origin_dst;
+ int src_slots, dst_slots, i, iter, step, skip_bits;
+ depot_stack_handle_t old_origin = 0, chain_origin, new_origin = 0;
+ u32 *align_shadow_src, shadow;
+ bool backwards;
+
+ shadow_dst = kmsan_get_metadata(dst, n, META_SHADOW);
+ if (!shadow_dst)
+ return;
+ BUG_ON(!metadata_is_contiguous(dst, n, META_SHADOW));
+
+ shadow_src = kmsan_get_metadata(src, n, META_SHADOW);
+ if (!shadow_src) {
+ /*
+ * |src| is untracked: zero out destination shadow, ignore the
+ * origins, we're done.
+ */
+ __memset(shadow_dst, 0, n);
+ return;
+ }
+ BUG_ON(!metadata_is_contiguous(src, n, META_SHADOW));
+
+ if (is_memmove)
+ __memmove(shadow_dst, shadow_src, n);
+ else
+ __memcpy(shadow_dst, shadow_src, n);
+
+ origin_dst = kmsan_get_metadata(dst, n, META_ORIGIN);
+ origin_src = kmsan_get_metadata(src, n, META_ORIGIN);
+ BUG_ON(!origin_dst || !origin_src);
+ BUG_ON(!metadata_is_contiguous(dst, n, META_ORIGIN));
+ BUG_ON(!metadata_is_contiguous(src, n, META_ORIGIN));
+ src_slots = (ALIGN((u64)src + n, ORIGIN_SIZE) -
+ ALIGN_DOWN((u64)src, ORIGIN_SIZE)) / ORIGIN_SIZE;
+ dst_slots = (ALIGN((u64)dst + n, ORIGIN_SIZE) -
+ ALIGN_DOWN((u64)dst, ORIGIN_SIZE)) / ORIGIN_SIZE;
+ BUG_ON(!src_slots || !dst_slots);
+ BUG_ON((src_slots < 1) || (dst_slots < 1));
+ BUG_ON((src_slots - dst_slots > 1) || (dst_slots - src_slots < -1));
+
+ backwards = is_memmove && (dst > src);
+ i = backwards ? min(src_slots, dst_slots) - 1 : 0;
+ iter = backwards ? -1 : 1;
+
+ align_shadow_src = (u32 *)ALIGN_DOWN((u64)shadow_src, ORIGIN_SIZE);
+ for (step = 0; step < min(src_slots, dst_slots); step++, i += iter) {
+ BUG_ON(i < 0);
+ shadow = align_shadow_src[i];
+ if (i == 0) {
+ /*
+ * If |src| isn't aligned on ORIGIN_SIZE, don't
+ * look at the first |src % ORIGIN_SIZE| bytes
+ * of the first shadow slot.
+ */
+ skip_bits = ((u64)src % ORIGIN_SIZE) * 8;
+ shadow = (shadow << skip_bits) >> skip_bits;
+ }
+ if (i == src_slots - 1) {
+ /*
+ * If |src + n| isn't aligned on
+ * ORIGIN_SIZE, don't look at the last
+ * |(src + n) % ORIGIN_SIZE| bytes of the
+ * last shadow slot.
+ */
+ skip_bits = (((u64)src + n) % ORIGIN_SIZE) * 8;
+ shadow = (shadow >> skip_bits) << skip_bits;
+ }
+ /*
+ * Overwrite the origin only if the corresponding
+ * shadow is nonempty.
+ */
+ if (origin_src[i] && (origin_src[i] != old_origin) && shadow) {
+ old_origin = origin_src[i];
+ chain_origin = kmsan_internal_chain_origin(old_origin);
+ /*
+ * kmsan_internal_chain_origin() may return
+ * NULL, but we don't want to lose the previous
+ * origin value.
+ */
+ if (chain_origin)
+ new_origin = chain_origin;
+ else
+ new_origin = old_origin;
+ }
+ if (shadow)
+ origin_dst[i] = new_origin;
+ else
+ origin_dst[i] = 0;
+ }
+}
+
+void kmsan_memcpy_metadata(void *dst, void *src, size_t n)
+{
+ kmsan_memcpy_memmove_metadata(dst, src, n, /*is_memmove*/false);
+}
+
+void kmsan_memmove_metadata(void *dst, void *src, size_t n)
+{
+ kmsan_memcpy_memmove_metadata(dst, src, n, /*is_memmove*/true);
+}
+
+depot_stack_handle_t kmsan_internal_chain_origin(depot_stack_handle_t id)
+{
+ depot_stack_handle_t handle;
+ unsigned long entries[3];
+ u64 magic = KMSAN_CHAIN_MAGIC_ORIGIN_FULL;
+ int depth = 0;
+ static int skipped;
+ u32 extra_bits;
+ bool uaf;
+
+ if (!id)
+ return id;
+ /*
+ * Make sure we have enough spare bits in |id| to hold the UAF bit and
+ * the chain depth.
+ */
+ BUILD_BUG_ON((1 << STACK_DEPOT_EXTRA_BITS) <= (MAX_CHAIN_DEPTH << 1));
+
+ extra_bits = get_dsh_extra_bits(id);
+ depth = kmsan_depth_from_eb(extra_bits);
+ uaf = kmsan_uaf_from_eb(extra_bits);
+
+ if (depth >= MAX_CHAIN_DEPTH) {
+ skipped++;
+ if (skipped % 10000 == 0) {
+ pr_warn("not chained %d origins\n", skipped);
+ dump_stack();
+ kmsan_print_origin(id);
+ }
+ return id;
+ }
+ depth++;
+ extra_bits = kmsan_extra_bits(depth, uaf);
+
+ entries[0] = magic + depth;
+ entries[1] = kmsan_save_stack_with_flags(GFP_ATOMIC, extra_bits);
+ entries[2] = id;
+ handle = stack_depot_save(entries, ARRAY_SIZE(entries), GFP_ATOMIC);
+ return set_dsh_extra_bits(handle, extra_bits);
+}
+
+void kmsan_write_aligned_origin(void *var, size_t size, u32 origin)
+{
+ u32 *var_cast = (u32 *)var;
+ int i;
+
+ BUG_ON((u64)var_cast % ORIGIN_SIZE);
+ BUG_ON(size % ORIGIN_SIZE);
+ for (i = 0; i < size / ORIGIN_SIZE; i++)
+ var_cast[i] = origin;
+}
+
+void kmsan_internal_set_origin(void *addr, int size, u32 origin)
+{
+ void *origin_start;
+ u64 address = (u64)addr, page_offset;
+ size_t to_fill, pad = 0;
+
+ if (!IS_ALIGNED(address, ORIGIN_SIZE)) {
+ pad = address % ORIGIN_SIZE;
+ address -= pad;
+ size += pad;
+ }
+
+ while (size > 0) {
+ page_offset = address % PAGE_SIZE;
+ to_fill = min(PAGE_SIZE - page_offset, (u64)size);
+ /* write at least ORIGIN_SIZE bytes */
+ to_fill = ALIGN(to_fill, ORIGIN_SIZE);
+ BUG_ON(!to_fill);
+ origin_start = kmsan_get_metadata((void *)address, to_fill,
+ META_ORIGIN);
+ address += to_fill;
+ size -= to_fill;
+ if (!origin_start)
+ /* Can happen e.g. if the memory is untracked. */
+ continue;
+ kmsan_write_aligned_origin(origin_start, to_fill, origin);
+ }
+}
+
+void kmsan_set_origin_checked(void *addr, int size, u32 origin, bool checked)
+{
+ if (checked && !metadata_is_contiguous(addr, size, META_ORIGIN))
+ panic("%s: WARNING: not setting origin for %d bytes starting at %px, because the metadata is incontiguous\n",
+ __func__, size, addr);
+ kmsan_internal_set_origin(addr, size, origin);
+}
+
+struct page *vmalloc_to_page_or_null(void *vaddr)
+{
+ struct page *page;
+
+ if (!kmsan_internal_is_vmalloc_addr(vaddr) &&
+ !kmsan_internal_is_module_addr(vaddr))
+ return NULL;
+ page = vmalloc_to_page(vaddr);
+ if (pfn_valid(page_to_pfn(page)))
+ return page;
+ else
+ return NULL;
+}
+
+void kmsan_internal_check_memory(void *addr, size_t size, const void *user_addr,
+ int reason)
+{
+ unsigned long irq_flags;
+ unsigned long addr64 = (unsigned long)addr;
+ unsigned char *shadow = NULL;
+ depot_stack_handle_t *origin = NULL;
+ depot_stack_handle_t cur_origin = 0, new_origin = 0;
+ int cur_off_start = -1;
+ int i, chunk_size;
+ size_t pos = 0;
+
+ BUG_ON(!metadata_is_contiguous(addr, size, META_SHADOW));
+ if (size <= 0)
+ return;
+ while (pos < size) {
+ chunk_size = min(size - pos,
+ PAGE_SIZE - ((addr64 + pos) % PAGE_SIZE));
+ shadow = kmsan_get_metadata((void *)(addr64 + pos), chunk_size,
+ META_SHADOW);
+ if (!shadow) {
+ /*
+ * This page is untracked. If there were uninitialized
+ * bytes before, report them.
+ */
+ if (cur_origin) {
+ irq_flags = kmsan_enter_runtime();
+ kmsan_report(cur_origin, addr, size,
+ cur_off_start, pos - 1, user_addr,
+ reason);
+ kmsan_leave_runtime(irq_flags);
+ }
+ cur_origin = 0;
+ cur_off_start = -1;
+ pos += chunk_size;
+ continue;
+ }
+ for (i = 0; i < chunk_size; i++) {
+ if (!shadow[i]) {
+ /*
+ * This byte is unpoisoned. If there were
+ * poisoned bytes before, report them.
+ */
+ if (cur_origin) {
+ irq_flags = kmsan_enter_runtime();
+ kmsan_report(cur_origin, addr, size,
+ cur_off_start, pos + i - 1,
+ user_addr, reason);
+ kmsan_leave_runtime(irq_flags);
+ }
+ cur_origin = 0;
+ cur_off_start = -1;
+ continue;
+ }
+ origin = kmsan_get_metadata((void *)(addr64 + pos + i),
+ chunk_size - i, META_ORIGIN);
+ BUG_ON(!origin);
+ new_origin = *origin;
+ /*
+ * Encountered new origin - report the previous
+ * uninitialized range.
+ */
+ if (cur_origin != new_origin) {
+ if (cur_origin) {
+ irq_flags = kmsan_enter_runtime();
+ kmsan_report(cur_origin, addr, size,
+ cur_off_start, pos + i - 1,
+ user_addr, reason);
+ kmsan_leave_runtime(irq_flags);
+ }
+ cur_origin = new_origin;
+ cur_off_start = pos + i;
+ }
+ }
+ pos += chunk_size;
+ }
+ BUG_ON(pos != size);
+ if (cur_origin) {
+ irq_flags = kmsan_enter_runtime();
+ kmsan_report(cur_origin, addr, size, cur_off_start, pos - 1,
+ user_addr, reason);
+ kmsan_leave_runtime(irq_flags);
+ }
+}
+
+bool metadata_is_contiguous(void *addr, size_t size, bool is_origin)
+{
+ u64 cur_addr = (u64)addr, next_addr;
+ char *cur_meta = NULL, *next_meta = NULL;
+ depot_stack_handle_t *origin_p;
+ bool all_untracked = false;
+ const char *fname = is_origin ? "origin" : "shadow";
+
+ if (!size)
+ return true;
+
+ /* The whole range belongs to the same page. */
+ if (ALIGN_DOWN(cur_addr + size - 1, PAGE_SIZE) ==
+ ALIGN_DOWN(cur_addr, PAGE_SIZE))
+ return true;
+ cur_meta = kmsan_get_metadata((void *)cur_addr, 1, is_origin);
+ if (!cur_meta)
+ all_untracked = true;
+ for (next_addr = cur_addr + PAGE_SIZE; next_addr < (u64)addr + size;
+ cur_addr = next_addr,
+ cur_meta = next_meta,
+ next_addr += PAGE_SIZE) {
+ next_meta = kmsan_get_metadata((void *)next_addr, 1, is_origin);
+ if (!next_meta) {
+ if (!all_untracked)
+ goto report;
+ continue;
+ }
+ if ((u64)cur_meta == ((u64)next_meta - PAGE_SIZE))
+ continue;
+ goto report;
+ }
+ return true;
+
+report:
+ pr_err("BUG: attempting to access two shadow page ranges.\n");
+ dump_stack();
+ pr_err("\n");
+ pr_err("Access of size %d at %px.\n", size, addr);
+ pr_err("Addresses belonging to different ranges: %px and %px\n",
+ cur_addr, next_addr);
+ pr_err("page[0].%s: %px, page[1].%s: %px\n",
+ fname, cur_meta, fname, next_meta);
+ origin_p = kmsan_get_metadata(addr, 1, META_ORIGIN);
+ if (origin_p) {
+ pr_err("Origin: %08x\n", *origin_p);
+ kmsan_print_origin(*origin_p);
+ } else {
+ pr_err("Origin: unavailable\n");
+ }
+ return false;
+}
+
+/*
+ * Dummy replacement for __builtin_return_address() which may crash without
+ * frame pointers.
+ */
+void *kmsan_internal_return_address(int arg)
+{
+#ifdef CONFIG_UNWINDER_FRAME_POINTER
+ switch (arg) {
+ case 1:
+ return __builtin_return_address(1);
+ case 2:
+ return __builtin_return_address(2);
+ default:
+ BUG();
+ }
+#else
+ unsigned long entries[1];
+
+ stack_trace_save(entries, 1, arg);
+ return (void *)entries[0];
+#endif
+}
+
+bool kmsan_internal_is_module_addr(void *vaddr)
+{
+ return ((u64)vaddr >= MODULES_VADDR) && ((u64)vaddr < MODULES_END);
+}
+
+bool kmsan_internal_is_vmalloc_addr(void *addr)
+{
+ return ((u64)addr >= VMALLOC_START) && ((u64)addr < VMALLOC_END);
+}
diff --git a/mm/kmsan/kmsan.h b/mm/kmsan/kmsan.h
new file mode 100644
index 0000000000000..9568b0005b5e7
--- /dev/null
+++ b/mm/kmsan/kmsan.h
@@ -0,0 +1,161 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * KMSAN internal declarations.
+ *
+ * Copyright (C) 2017-2019 Google LLC
+ * Author: Alexander Potapenko <glider@xxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#ifndef __MM_KMSAN_KMSAN_H
+#define __MM_KMSAN_KMSAN_H
+
+#include <asm/pgtable_64_types.h>
+#include <linux/irqflags.h>
+#include <linux/sched.h>
+#include <linux/stackdepot.h>
+#include <linux/stacktrace.h>
+#include <linux/nmi.h>
+#include <linux/mm.h>
+#include <linux/printk.h>
+
+#include "kmsan_shadow.h"
+
+#define KMSAN_MAGIC_MASK 0xffffffffff00
+#define KMSAN_ALLOCA_MAGIC_ORIGIN 0x4110c4071900
+#define KMSAN_CHAIN_MAGIC_ORIGIN_FULL 0xd419170cba00
+
+#define KMSAN_POISON_NOCHECK 0x0
+#define KMSAN_POISON_CHECK 0x1
+#define KMSAN_POISON_FREE 0x2
+
+#define ORIGIN_SIZE 4
+
+#define META_SHADOW (false)
+#define META_ORIGIN (true)
+
+#define KMSAN_NESTED_CONTEXT_MAX (8)
+/* [0] for dummy per-CPU context */
+DECLARE_PER_CPU(struct kmsan_context_state[KMSAN_NESTED_CONTEXT_MAX],
+ kmsan_percpu_cstate);
+/* 0 for task context, |i>0| for kmsan_context_state[i]. */
+DECLARE_PER_CPU(int, kmsan_context_level);
+
+extern spinlock_t report_lock;
+extern bool kmsan_ready;
+
+void kmsan_print_origin(depot_stack_handle_t origin);
+void kmsan_report(depot_stack_handle_t origin,
+ void *address, int size, int off_first, int off_last,
+ const void *user_addr, int reason);
+
+enum KMSAN_BUG_REASON {
+ REASON_ANY,
+ REASON_COPY_TO_USER,
+ REASON_USE_AFTER_FREE,
+ REASON_SUBMIT_URB,
+};
+
+/*
+ * When a compiler hook is invoked, it may make a call to instrumented code
+ * and eventually call itself recursively. To avoid that, we protect the
+ * runtime entry points with kmsan_enter_runtime()/kmsan_leave_runtime() and
+ * exit the hook if kmsan_in_runtime() is true. But when an interrupt occurs
+ * inside the runtime, the hooks won’t run either, which may lead to errors.
+ * Therefore we have to disable interrupts inside the runtime.
+ */
+DECLARE_PER_CPU(int, kmsan_in_runtime_cnt);
+
+static __always_inline bool kmsan_in_runtime(void)
+{
+ return this_cpu_read(kmsan_in_runtime_cnt);
+}
+
+static __always_inline unsigned long kmsan_enter_runtime(void)
+{
+ int level;
+ unsigned long irq_flags;
+
+ preempt_disable();
+ local_irq_save(irq_flags);
+ stop_nmi();
+ level = this_cpu_inc_return(kmsan_in_runtime_cnt);
+ BUG_ON(level > 1);
+ return irq_flags;
+}
+
+static __always_inline void kmsan_leave_runtime(unsigned long irq_flags)
+{
+ int level = this_cpu_dec_return(kmsan_in_runtime_cnt);
+
+ if (level)
+ panic("kmsan_in_runtime: %d\n", level);
+ restart_nmi();
+ local_irq_restore(irq_flags);
+ preempt_enable();
+}
+
+void kmsan_memcpy_metadata(void *dst, void *src, size_t n);
+void kmsan_memmove_metadata(void *dst, void *src, size_t n);
+
+depot_stack_handle_t kmsan_save_stack(void);
+depot_stack_handle_t kmsan_save_stack_with_flags(gfp_t flags,
+ unsigned int extra_bits);
+
+/*
+ * Pack and unpack the origin chain depth and UAF flag to/from the extra bits
+ * provided by the stack depot.
+ * The UAF flag is stored in the lowest bit, followed by the depth in the upper
+ * bits.
+ * set_dsh_extra_bits() is responsible for clamping the value.
+ */
+static __always_inline unsigned int kmsan_extra_bits(unsigned int depth,
+ bool uaf)
+{
+ return (depth << 1) | uaf;
+}
+
+static __always_inline bool kmsan_uaf_from_eb(unsigned int extra_bits)
+{
+ return extra_bits & 1;
+}
+
+static __always_inline unsigned int kmsan_depth_from_eb(unsigned int extra_bits)
+{
+ return extra_bits >> 1;
+}
+
+void kmsan_internal_poison_shadow(void *address, size_t size, gfp_t flags,
+ unsigned int poison_flags);
+void kmsan_internal_unpoison_shadow(void *address, size_t size, bool checked);
+void kmsan_internal_memset_shadow(void *address, int b, size_t size,
+ bool checked);
+depot_stack_handle_t kmsan_internal_chain_origin(depot_stack_handle_t id);
+void kmsan_write_aligned_origin(void *var, size_t size, u32 origin);
+
+void kmsan_internal_task_create(struct task_struct *task);
+void kmsan_internal_set_origin(void *addr, int size, u32 origin);
+void kmsan_set_origin_checked(void *addr, int size, u32 origin, bool checked);
+
+struct kmsan_context_state *kmsan_task_context_state(void);
+
+bool metadata_is_contiguous(void *addr, size_t size, bool is_origin);
+void kmsan_internal_check_memory(void *addr, size_t size, const void *user_addr,
+ int reason);
+
+struct page *vmalloc_to_page_or_null(void *vaddr);
+
+/* Declared in mm/vmalloc.c */
+void __vunmap_page_range(unsigned long addr, unsigned long end);
+int __vmap_page_range_noflush(unsigned long start, unsigned long end,
+ pgprot_t prot, struct page **pages);
+
+void *kmsan_internal_return_address(int arg);
+bool kmsan_internal_is_module_addr(void *vaddr);
+bool kmsan_internal_is_vmalloc_addr(void *addr);
+
+#endif /* __MM_KMSAN_KMSAN_H */
diff --git a/mm/kmsan/kmsan_init.c b/mm/kmsan/kmsan_init.c
new file mode 100644
index 0000000000000..12c84efa70ff9
--- /dev/null
+++ b/mm/kmsan/kmsan_init.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KMSAN initialization routines.
+ *
+ * Copyright (C) 2017-2019 Google LLC
+ * Author: Alexander Potapenko <glider@xxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include "kmsan.h"
+
+#include <asm/cpu_entry_area.h>
+#include <asm/sections.h>
+#include <linux/mm.h>
+#include <linux/memblock.h>
+
+#define NUM_FUTURE_RANGES 128
+struct start_end_pair {
+ void *start, *end;
+};
+
+static struct start_end_pair start_end_pairs[NUM_FUTURE_RANGES] __initdata;
+static int future_index __initdata;
+
+/*
+ * Record a range of memory for which the metadata pages will be created once
+ * the page allocator becomes available.
+ */
+static void __init kmsan_record_future_shadow_range(void *start, void *end)
+{
+ BUG_ON(future_index == NUM_FUTURE_RANGES);
+ BUG_ON((start >= end) || !start || !end);
+ start_end_pairs[future_index].start = start;
+ start_end_pairs[future_index].end = end;
+ future_index++;
+}
+
+/*
+ * Initialize the shadow for existing mappings during kernel initialization.
+ * These include kernel text/data sections, NODE_DATA and future ranges
+ * registered while creating other data (e.g. percpu).
+ *
+ * Allocations via memblock can be only done before slab is initialized.
+ */
+void __init kmsan_initialize_shadow(void)
+{
+ int nid;
+ u64 i;
+ const size_t nd_size = roundup(sizeof(pg_data_t), PAGE_SIZE);
+ phys_addr_t p_start, p_end;
+
+ for_each_reserved_mem_region(i, &p_start, &p_end)
+ kmsan_record_future_shadow_range(phys_to_virt(p_start),
+ phys_to_virt(p_end+1));
+ /* Allocate shadow for .data */
+ kmsan_record_future_shadow_range(_sdata, _edata);
+
+ for_each_online_node(nid)
+ kmsan_record_future_shadow_range(
+ NODE_DATA(nid), (char *)NODE_DATA(nid) + nd_size);
+
+ for (i = 0; i < future_index; i++)
+ kmsan_init_alloc_meta_for_range(start_end_pairs[i].start,
+ start_end_pairs[i].end);
+}
+EXPORT_SYMBOL(kmsan_initialize_shadow);
+
+void __init kmsan_initialize(void)
+{
+ /* Assuming current is init_task */
+ kmsan_internal_task_create(current);
+ pr_info("Starting KernelMemorySanitizer\n");
+ kmsan_ready = true;
+}
+EXPORT_SYMBOL(kmsan_initialize);
diff --git a/mm/kmsan/kmsan_report.c b/mm/kmsan/kmsan_report.c
new file mode 100644
index 0000000000000..7455fa7d10bb2
--- /dev/null
+++ b/mm/kmsan/kmsan_report.c
@@ -0,0 +1,143 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KMSAN error reporting routines.
+ *
+ * Copyright (C) 2019 Google LLC
+ * Author: Alexander Potapenko <glider@xxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/console.h>
+#include <linux/stackdepot.h>
+#include <linux/stacktrace.h>
+
+#include "kmsan.h"
+
+DEFINE_SPINLOCK(report_lock);
+
+void kmsan_print_origin(depot_stack_handle_t origin)
+{
+ unsigned long *entries = NULL, *chained_entries = NULL;
+ unsigned long nr_entries, chained_nr_entries, magic;
+ char *descr = NULL;
+ void *pc1 = NULL, *pc2 = NULL;
+ depot_stack_handle_t head;
+
+ if (!origin)
+ return;
+
+ while (true) {
+ nr_entries = stack_depot_fetch(origin, &entries);
+ magic = nr_entries ? (entries[0] & KMSAN_MAGIC_MASK) : 0;
+ if ((nr_entries == 4) && (magic == KMSAN_ALLOCA_MAGIC_ORIGIN)) {
+ descr = (char *)entries[1];
+ pc1 = (void *)entries[2];
+ pc2 = (void *)entries[3];
+ pr_err("Local variable %s created at:\n", descr);
+ pr_err(" %pS\n", pc1);
+ pr_err(" %pS\n", pc2);
+ break;
+ }
+ if ((nr_entries == 3) &&
+ (magic == KMSAN_CHAIN_MAGIC_ORIGIN_FULL)) {
+ head = entries[1];
+ origin = entries[2];
+ pr_err("Uninit was stored to memory at:\n");
+ chained_nr_entries =
+ stack_depot_fetch(head, &chained_entries);
+ stack_trace_print(chained_entries, chained_nr_entries,
+ 0);
+ pr_err("\n");
+ continue;
+ }
+ pr_err("Uninit was created at:\n");
+ if (nr_entries)
+ stack_trace_print(entries, nr_entries, 0);
+ else
+ pr_err("(stack is not available)\n");
+ break;
+ }
+}
+
+/**
+ * kmsan_report() - Report a use of uninitialized value.
+ * @origin: Stack ID of the uninitialized value.
+ * @address: Address at which the memory access happens.
+ * @size: Memory access size.
+ * @off_first: Offset (from @address) of the first byte to be reported.
+ * @off_last: Offset (from @address) of the last byte to be reported.
+ * @user_addr: When non-NULL, denotes the userspace address to which the kernel
+ * is leaking data.
+ * @reason: Error type from KMSAN_BUG_REASON enum.
+ *
+ * kmsan_report() prints an error message for a consequent group of bytes
+ * sharing the same origin. If an uninitialized value is used in a comparison,
+ * this function is called once without specifying the addresses. When checking
+ * a memory range, KMSAN may call kmsan_report() multiple times with the same
+ * @address, @size, @user_addr and @reason, but different @off_first and
+ * @off_last corresponding to different @origin values.
+ */
+void kmsan_report(depot_stack_handle_t origin,
+ void *address, int size, int off_first, int off_last,
+ const void *user_addr, int reason)
+{
+ unsigned long flags;
+ bool is_uaf;
+ char *bug_type = NULL;
+
+ if (!kmsan_ready)
+ return;
+ if (!current->kmsan.allow_reporting)
+ return;
+ if (!origin)
+ return;
+
+ current->kmsan.allow_reporting = false;
+ spin_lock_irqsave(&report_lock, flags);
+ pr_err("=====================================================\n");
+ is_uaf = kmsan_uaf_from_eb(get_dsh_extra_bits(origin));
+ switch (reason) {
+ case REASON_ANY:
+ bug_type = is_uaf ? "use-after-free" : "uninit-value";
+ break;
+ case REASON_COPY_TO_USER:
+ bug_type = is_uaf ? "kernel-infoleak-after-free" :
+ "kernel-infoleak";
+ break;
+ case REASON_SUBMIT_URB:
+ bug_type = is_uaf ? "kernel-usb-infoleak-after-free" :
+ "kernel-usb-infoleak";
+ break;
+ }
+ pr_err("BUG: KMSAN: %s in %pS\n",
+ bug_type, kmsan_internal_return_address(2));
+ dump_stack();
+ pr_err("\n");
+
+ kmsan_print_origin(origin);
+
+ if (size) {
+ pr_err("\n");
+ if (off_first == off_last)
+ pr_err("Byte %d of %d is uninitialized\n",
+ off_first, size);
+ else
+ pr_err("Bytes %d-%d of %d are uninitialized\n",
+ off_first, off_last, size);
+ }
+ if (address)
+ pr_err("Memory access of size %d starts at %px\n",
+ size, address);
+ if (user_addr && reason == REASON_COPY_TO_USER)
+ pr_err("Data copied to user address %px\n", user_addr);
+ pr_err("=====================================================\n");
+ add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
+ spin_unlock_irqrestore(&report_lock, flags);
+ if (panic_on_warn)
+ panic("panic_on_warn set ...\n");
+ current->kmsan.allow_reporting = true;
+}
diff --git a/mm/kmsan/kmsan_shadow.c b/mm/kmsan/kmsan_shadow.c
new file mode 100644
index 0000000000000..bcd4f1faa7a67
--- /dev/null
+++ b/mm/kmsan/kmsan_shadow.c
@@ -0,0 +1,456 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KMSAN shadow implementation.
+ *
+ * Copyright (C) 2017-2019 Google LLC
+ * Author: Alexander Potapenko <glider@xxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <asm/cpu_entry_area.h>
+#include <asm/page.h>
+#include <asm/pgtable_64_types.h>
+#include <asm/tlbflush.h>
+#include <linux/memblock.h>
+#include <linux/mm_types.h>
+#include <linux/percpu-defs.h>
+#include <linux/slab.h>
+#include <linux/smp.h>
+#include <linux/stddef.h>
+
+#include "kmsan.h"
+#include "kmsan_shadow.h"
+
+#define shadow_page_for(page) ((page)->shadow)
+
+#define origin_page_for(page) ((page)->origin)
+
+#define shadow_ptr_for(page) (page_address((page)->shadow))
+
+#define origin_ptr_for(page) (page_address((page)->origin))
+
+#define has_shadow_page(page) (!!((page)->shadow))
+
+#define has_origin_page(page) (!!((page)->origin))
+
+#define set_no_shadow_origin_page(page) \
+ do { \
+ (page)->shadow = NULL; \
+ (page)->origin = NULL; \
+ } while (0) /**/
+
+#define is_ignored_page(page) (!!(((u64)((page)->shadow)) % 2))
+
+#define ignore_page(pg) \
+ ((pg)->shadow = (struct page *)((u64)((pg)->shadow) | 1))
+
+DEFINE_PER_CPU(char[CPU_ENTRY_AREA_SIZE], cpu_entry_area_shadow);
+DEFINE_PER_CPU(char[CPU_ENTRY_AREA_SIZE], cpu_entry_area_origin);
+
+/*
+ * Dummy load and store pages to be used when the real metadata is unavailable.
+ * There are separate pages for loads and stores, so that every load returns a
+ * zero, and every store doesn't affect other loads.
+ */
+char dummy_load_page[PAGE_SIZE] __aligned(PAGE_SIZE);
+char dummy_store_page[PAGE_SIZE] __aligned(PAGE_SIZE);
+
+/*
+ * Taken from arch/x86/mm/physaddr.h to avoid using an instrumented version.
+ */
+static int kmsan_phys_addr_valid(unsigned long addr)
+{
+#ifdef CONFIG_PHYS_ADDR_T_64BIT
+ return !(addr >> boot_cpu_data.x86_phys_bits);
+#else
+ return 1;
+#endif
+}
+
+/*
+ * Taken from arch/x86/mm/physaddr.c to avoid using an instrumented version.
+ */
+static bool kmsan_virt_addr_valid(void *addr)
+{
+ unsigned long x = (unsigned long)addr;
+ unsigned long y = x - __START_KERNEL_map;
+
+ /* use the carry flag to determine if x was < __START_KERNEL_map */
+ if (unlikely(x > y)) {
+ x = y + phys_base;
+
+ if (y >= KERNEL_IMAGE_SIZE)
+ return false;
+ } else {
+ x = y + (__START_KERNEL_map - PAGE_OFFSET);
+
+ /* carry flag will be set if starting x was >= PAGE_OFFSET */
+ if ((x > y) || !kmsan_phys_addr_valid(x))
+ return false;
+ }
+
+ return pfn_valid(x >> PAGE_SHIFT);
+}
+
+static unsigned long vmalloc_meta(void *addr, bool is_origin)
+{
+ unsigned long addr64 = (unsigned long)addr, off;
+
+ BUG_ON(is_origin && !IS_ALIGNED(addr64, ORIGIN_SIZE));
+ if (kmsan_internal_is_vmalloc_addr(addr))
+ return addr64 + (is_origin ? VMALLOC_ORIGIN_OFFSET
+ : VMALLOC_SHADOW_OFFSET);
+ if (kmsan_internal_is_module_addr(addr)) {
+ off = addr64 - MODULES_VADDR;
+ return off + (is_origin ? MODULES_ORIGIN_START
+ : MODULES_SHADOW_START);
+ }
+ return 0;
+}
+
+static void *get_cea_meta_or_null(void *addr, bool is_origin)
+{
+ int cpu = smp_processor_id();
+ int off;
+ char *metadata_array;
+
+ if (((u64)addr < CPU_ENTRY_AREA_BASE) ||
+ ((u64)addr >= (CPU_ENTRY_AREA_BASE + CPU_ENTRY_AREA_MAP_SIZE)))
+ return NULL;
+ off = (char *)addr - (char *)get_cpu_entry_area(cpu);
+ if ((off < 0) || (off >= CPU_ENTRY_AREA_SIZE))
+ return NULL;
+ metadata_array = is_origin ? cpu_entry_area_origin :
+ cpu_entry_area_shadow;
+ return &per_cpu(metadata_array[off], cpu);
+}
+
+static struct page *virt_to_page_or_null(void *vaddr)
+{
+ if (kmsan_virt_addr_valid(vaddr))
+ return virt_to_page(vaddr);
+ else
+ return NULL;
+}
+
+struct shadow_origin_ptr kmsan_get_shadow_origin_ptr(void *address, u64 size,
+ bool store)
+{
+ struct shadow_origin_ptr ret;
+ void *shadow;
+
+ if (size > PAGE_SIZE)
+ panic("size too big in %s(%px, %d, %d)\n",
+ __func__, address, size, store);
+
+ if (!kmsan_ready || kmsan_in_runtime())
+ goto return_dummy;
+
+ BUG_ON(!metadata_is_contiguous(address, size, META_SHADOW));
+ shadow = kmsan_get_metadata(address, size, META_SHADOW);
+ if (!shadow)
+ goto return_dummy;
+
+ ret.s = shadow;
+ ret.o = kmsan_get_metadata(address, size, META_ORIGIN);
+ return ret;
+
+return_dummy:
+ if (store) {
+ ret.s = dummy_store_page;
+ ret.o = dummy_store_page;
+ } else {
+ ret.s = dummy_load_page;
+ ret.o = dummy_load_page;
+ }
+ return ret;
+}
+
+/*
+ * Obtain the shadow or origin pointer for the given address, or NULL if there's
+ * none. The caller must check the return value for being non-NULL if needed.
+ * The return value of this function should not depend on whether we're in the
+ * runtime or not.
+ */
+void *kmsan_get_metadata(void *address, size_t size, bool is_origin)
+{
+ struct page *page;
+ void *ret;
+ u64 addr = (u64)address, pad, off;
+
+ if (is_origin && !IS_ALIGNED(addr, ORIGIN_SIZE)) {
+ pad = addr % ORIGIN_SIZE;
+ addr -= pad;
+ size += pad;
+ }
+ address = (void *)addr;
+ if (kmsan_internal_is_vmalloc_addr(address) ||
+ kmsan_internal_is_module_addr(address))
+ return (void *)vmalloc_meta(address, is_origin);
+
+ ret = get_cea_meta_or_null(address, is_origin);
+ if (ret)
+ return ret;
+
+ page = virt_to_page_or_null(address);
+ if (!page)
+ return NULL;
+ if (is_ignored_page(page))
+ return NULL;
+ if (!has_shadow_page(page) || !has_origin_page(page))
+ return NULL;
+ off = addr % PAGE_SIZE;
+
+ ret = (is_origin ? origin_ptr_for(page) : shadow_ptr_for(page)) + off;
+ return ret;
+}
+
+void __init kmsan_init_alloc_meta_for_range(void *start, void *end)
+{
+ u64 addr, size;
+ struct page *page;
+ void *shadow, *origin;
+ struct page *shadow_p, *origin_p;
+
+ start = (void *)ALIGN_DOWN((u64)start, PAGE_SIZE);
+ size = ALIGN((u64)end - (u64)start, PAGE_SIZE);
+ shadow = memblock_alloc(size, PAGE_SIZE);
+ origin = memblock_alloc(size, PAGE_SIZE);
+ for (addr = 0; addr < size; addr += PAGE_SIZE) {
+ page = virt_to_page_or_null((char *)start + addr);
+ shadow_p = virt_to_page_or_null((char *)shadow + addr);
+ set_no_shadow_origin_page(shadow_p);
+ shadow_page_for(page) = shadow_p;
+ origin_p = virt_to_page_or_null((char *)origin + addr);
+ set_no_shadow_origin_page(origin_p);
+ origin_page_for(page) = origin_p;
+ }
+}
+
+/* Called from mm/memory.c */
+void kmsan_copy_page_meta(struct page *dst, struct page *src)
+{
+ unsigned long irq_flags;
+
+ if (!kmsan_ready || kmsan_in_runtime())
+ return;
+ if (!has_shadow_page(src)) {
+ kmsan_internal_unpoison_shadow(page_address(dst), PAGE_SIZE,
+ /*checked*/false);
+ return;
+ }
+ if (!has_shadow_page(dst))
+ return;
+ if (is_ignored_page(src)) {
+ ignore_page(dst);
+ return;
+ }
+
+ irq_flags = kmsan_enter_runtime();
+ __memcpy(shadow_ptr_for(dst), shadow_ptr_for(src),
+ PAGE_SIZE);
+ BUG_ON(!has_origin_page(src) || !has_origin_page(dst));
+ __memcpy(origin_ptr_for(dst), origin_ptr_for(src),
+ PAGE_SIZE);
+ kmsan_leave_runtime(irq_flags);
+}
+EXPORT_SYMBOL(kmsan_copy_page_meta);
+
+/* Helper function to allocate page metadata. */
+static int kmsan_internal_alloc_meta_for_pages(struct page *page,
+ unsigned int order,
+ gfp_t flags, int node)
+{
+ struct page *shadow, *origin;
+ int pages = 1 << order;
+ int i;
+ bool initialized = (flags & __GFP_ZERO) || !kmsan_ready;
+ depot_stack_handle_t handle;
+
+ if (flags & __GFP_NO_KMSAN_SHADOW) {
+ for (i = 0; i < pages; i++)
+ set_no_shadow_origin_page(&page[i]);
+ return 0;
+ }
+
+ /*
+ * We always want metadata allocations to succeed and to finish fast.
+ */
+ flags = GFP_ATOMIC;
+ if (initialized)
+ flags |= __GFP_ZERO;
+ shadow = alloc_pages_node(node, flags | __GFP_NO_KMSAN_SHADOW, order);
+ if (!shadow) {
+ for (i = 0; i < pages; i++) {
+ set_no_shadow_origin_page(&page[i]);
+ set_no_shadow_origin_page(&page[i]);
+ }
+ return -ENOMEM;
+ }
+ if (!initialized)
+ __memset(page_address(shadow), -1, PAGE_SIZE * pages);
+
+ origin = alloc_pages_node(node, flags | __GFP_NO_KMSAN_SHADOW, order);
+ /* Assume we've allocated the origin. */
+ if (!origin) {
+ __free_pages(shadow, order);
+ for (i = 0; i < pages; i++)
+ set_no_shadow_origin_page(&page[i]);
+ return -ENOMEM;
+ }
+
+ if (!initialized) {
+ handle = kmsan_save_stack_with_flags(flags, /*extra_bits*/0);
+ /*
+ * Addresses are page-aligned, pages are contiguous, so it's ok
+ * to just fill the origin pages with |handle|.
+ */
+ for (i = 0; i < PAGE_SIZE * pages / sizeof(handle); i++) {
+ ((depot_stack_handle_t *)page_address(origin))[i] =
+ handle;
+ }
+ }
+
+ for (i = 0; i < pages; i++) {
+ shadow_page_for(&page[i]) = &shadow[i];
+ set_no_shadow_origin_page(shadow_page_for(&page[i]));
+ origin_page_for(&page[i]) = &origin[i];
+ set_no_shadow_origin_page(origin_page_for(&page[i]));
+ }
+ return 0;
+}
+
+/* Called from mm/page_alloc.c */
+int kmsan_alloc_page(struct page *page, unsigned int order, gfp_t flags)
+{
+ unsigned long irq_flags;
+ int ret;
+
+ if (kmsan_in_runtime())
+ return 0;
+ irq_flags = kmsan_enter_runtime();
+ ret = kmsan_internal_alloc_meta_for_pages(page, order, flags, -1);
+ kmsan_leave_runtime(irq_flags);
+ return ret;
+}
+
+/* Called from mm/page_alloc.c */
+void kmsan_free_page(struct page *page, unsigned int order)
+{
+ struct page *shadow, *origin, *cur_page;
+ int pages = 1 << order;
+ int i;
+ unsigned long irq_flags;
+
+ if (!shadow_page_for(page)) {
+ for (i = 0; i < pages; i++) {
+ cur_page = &page[i];
+ BUG_ON(shadow_page_for(cur_page));
+ }
+ return;
+ }
+
+ if (!kmsan_ready) {
+ for (i = 0; i < pages; i++) {
+ cur_page = &page[i];
+ set_no_shadow_origin_page(cur_page);
+ }
+ return;
+ }
+
+ irq_flags = kmsan_enter_runtime();
+ shadow = shadow_page_for(&page[0]);
+ origin = origin_page_for(&page[0]);
+
+ for (i = 0; i < pages; i++) {
+ BUG_ON(has_shadow_page(shadow_page_for(&page[i])));
+ BUG_ON(has_shadow_page(origin_page_for(&page[i])));
+ set_no_shadow_origin_page(&page[i]);
+ }
+ BUG_ON(has_shadow_page(shadow));
+ __free_pages(shadow, order);
+
+ BUG_ON(has_shadow_page(origin));
+ __free_pages(origin, order);
+ kmsan_leave_runtime(irq_flags);
+}
+EXPORT_SYMBOL(kmsan_free_page);
+
+/* Called from mm/page_alloc.c */
+void kmsan_split_page(struct page *page, unsigned int order)
+{
+ struct page *shadow, *origin;
+ unsigned long irq_flags;
+
+ if (!kmsan_ready || kmsan_in_runtime())
+ return;
+
+ irq_flags = kmsan_enter_runtime();
+ if (!has_shadow_page(&page[0])) {
+ BUG_ON(has_origin_page(&page[0]));
+ kmsan_leave_runtime(irq_flags);
+ return;
+ }
+ shadow = shadow_page_for(&page[0]);
+ split_page(shadow, order);
+
+ origin = origin_page_for(&page[0]);
+ split_page(origin, order);
+ kmsan_leave_runtime(irq_flags);
+}
+EXPORT_SYMBOL(kmsan_split_page);
+
+/* Called from mm/vmalloc.c */
+void kmsan_vmap_page_range_noflush(unsigned long start, unsigned long end,
+ pgprot_t prot, struct page **pages)
+{
+ int nr, i, mapped;
+ struct page **s_pages, **o_pages;
+ unsigned long shadow_start, shadow_end, origin_start, origin_end;
+
+ if (!kmsan_ready || kmsan_in_runtime())
+ return;
+ shadow_start = vmalloc_meta((void *)start, META_SHADOW);
+ if (!shadow_start)
+ return;
+
+ BUG_ON(start >= end);
+ nr = (end - start) / PAGE_SIZE;
+ s_pages = kcalloc(nr, sizeof(struct page *), GFP_KERNEL);
+ o_pages = kcalloc(nr, sizeof(struct page *), GFP_KERNEL);
+ if (!s_pages || !o_pages)
+ goto ret;
+ for (i = 0; i < nr; i++) {
+ s_pages[i] = shadow_page_for(pages[i]);
+ o_pages[i] = origin_page_for(pages[i]);
+ }
+ prot = __pgprot(pgprot_val(prot) | _PAGE_NX);
+ prot = PAGE_KERNEL;
+
+ shadow_end = vmalloc_meta((void *)end, META_SHADOW);
+ origin_start = vmalloc_meta((void *)start, META_ORIGIN);
+ origin_end = vmalloc_meta((void *)end, META_ORIGIN);
+ mapped = __vmap_page_range_noflush(shadow_start, shadow_end,
+ prot, s_pages);
+ BUG_ON(mapped != nr);
+ flush_tlb_kernel_range(shadow_start, shadow_end);
+ mapped = __vmap_page_range_noflush(origin_start, origin_end,
+ prot, o_pages);
+ BUG_ON(mapped != nr);
+ flush_tlb_kernel_range(origin_start, origin_end);
+ret:
+ kfree(s_pages);
+ kfree(o_pages);
+}
+
+void kmsan_ignore_page(struct page *page, int order)
+{
+ int i;
+
+ for (i = 0; i < 1 << order; i++)
+ ignore_page(&page[i]);
+}
diff --git a/mm/kmsan/kmsan_shadow.h b/mm/kmsan/kmsan_shadow.h
new file mode 100644
index 0000000000000..eaa7f771b6a52
--- /dev/null
+++ b/mm/kmsan/kmsan_shadow.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * KMSAN shadow API.
+ *
+ * This should be agnostic to shadow implementation details.
+ *
+ * Copyright (C) 2017-2019 Google LLC
+ * Author: Alexander Potapenko <glider@xxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#ifndef __MM_KMSAN_KMSAN_SHADOW_H
+#define __MM_KMSAN_KMSAN_SHADOW_H
+
+#include <asm/cpu_entry_area.h> /* for CPU_ENTRY_AREA_MAP_SIZE */
+
+struct shadow_origin_ptr {
+ void *s, *o;
+};
+
+struct shadow_origin_ptr kmsan_get_shadow_origin_ptr(void *addr, u64 size,
+ bool store);
+void *kmsan_get_metadata(void *addr, size_t size, bool is_origin);
+void __init kmsan_init_alloc_meta_for_range(void *start, void *end);
+
+#endif /* __MM_KMSAN_KMSAN_SHADOW_H */
diff --git a/scripts/Makefile.kmsan b/scripts/Makefile.kmsan
new file mode 100644
index 0000000000000..8b3844b66b228
--- /dev/null
+++ b/scripts/Makefile.kmsan
@@ -0,0 +1,12 @@
+ifdef CONFIG_KMSAN
+
+CFLAGS_KMSAN := -fsanitize=kernel-memory
+
+ifeq ($(call cc-option, $(CFLAGS_KMSAN) -Werror),)
+ ifneq ($(CONFIG_COMPILE_TEST),y)
+ $(warning Cannot use CONFIG_KMSAN: \
+ -fsanitize=kernel-memory is not supported by compiler)
+ endif
+endif
+
+endif
--
2.25.1.696.g5e7596f4ac-goog
