The patch titled
Subject: dma: kmsan: unpoison DMA mappings
has been added to the -mm mm-unstable branch. Its filename is
dma-kmsan-unpoison-dma-mappings.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/dma-kmsan-unpoison-dma-mappings.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Alexander Potapenko <glider@xxxxxxxxxx>
Subject: dma: kmsan: unpoison DMA mappings
Date: Fri, 26 Aug 2022 17:07:45 +0200
KMSAN doesn't know about DMA memory writes performed by devices. We
unpoison such memory when it's mapped to avoid false positive reports.
Link: https://lkml.kernel.org/r/20220826150807.723137-23-glider@xxxxxxxxxx
Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Eric Biggers <ebiggers@xxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Cc: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Petr Mladek <pmladek@xxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Cc: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/kmsan.h | 41 +++++++++++++++++++++++++++
kernel/dma/mapping.c | 9 ++++--
mm/kmsan/hooks.c | 59 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 106 insertions(+), 3 deletions(-)
--- a/include/linux/kmsan.h~dma-kmsan-unpoison-dma-mappings
+++ a/include/linux/kmsan.h
@@ -9,6 +9,7 @@
#ifndef _LINUX_KMSAN_H
#define _LINUX_KMSAN_H
+#include <linux/dma-direction.h>
#include <linux/gfp.h>
#include <linux/kmsan-checks.h>
#include <linux/stackdepot.h>
@@ -17,6 +18,7 @@
struct page;
struct kmem_cache;
struct task_struct;
+struct scatterlist;
#ifdef CONFIG_KMSAN
@@ -196,6 +198,35 @@ void kmsan_ioremap_page_range(unsigned l
*/
void kmsan_iounmap_page_range(unsigned long start, unsigned long end);
+/**
+ * kmsan_handle_dma() - Handle a DMA data transfer.
+ * @page: first page of the buffer.
+ * @offset: offset of the buffer within the first page.
+ * @size: buffer size.
+ * @dir: 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(struct page *page, size_t offset, size_t size,
+ enum dma_data_direction dir);
+
+/**
+ * kmsan_handle_dma_sg() - Handle a DMA transfer using scatterlist.
+ * @sg: scatterlist holding DMA buffers.
+ * @nents: number of scatterlist entries.
+ * @dir: one of possible dma_data_direction values.
+ *
+ * Depending on @direction, KMSAN:
+ * * checks the buffers in the scatterlist, if they are copied to device;
+ * * initializes the buffers, if they are copied from device;
+ * * does both, if this is a DMA_BIDIRECTIONAL transfer.
+ */
+void kmsan_handle_dma_sg(struct scatterlist *sg, int nents,
+ enum dma_data_direction dir);
+
#else
static inline void kmsan_init_shadow(void)
@@ -278,6 +309,16 @@ static inline void kmsan_iounmap_page_ra
{
}
+static inline void kmsan_handle_dma(struct page *page, size_t offset,
+ size_t size, enum dma_data_direction dir)
+{
+}
+
+static inline void kmsan_handle_dma_sg(struct scatterlist *sg, int nents,
+ enum dma_data_direction dir)
+{
+}
+
#endif
#endif /* _LINUX_KMSAN_H */
--- a/kernel/dma/mapping.c~dma-kmsan-unpoison-dma-mappings
+++ a/kernel/dma/mapping.c
@@ -156,6 +156,7 @@ dma_addr_t dma_map_page_attrs(struct dev
addr = dma_direct_map_page(dev, page, offset, size, dir, attrs);
else
addr = ops->map_page(dev, page, offset, size, dir, attrs);
+ kmsan_handle_dma(page, offset, size, dir);
debug_dma_map_page(dev, page, offset, size, dir, addr, attrs);
return addr;
@@ -194,11 +195,13 @@ static int __dma_map_sg_attrs(struct dev
else
ents = ops->map_sg(dev, sg, nents, dir, attrs);
- if (ents > 0)
+ if (ents > 0) {
+ kmsan_handle_dma_sg(sg, nents, dir);
debug_dma_map_sg(dev, sg, nents, ents, dir, attrs);
- else if (WARN_ON_ONCE(ents != -EINVAL && ents != -ENOMEM &&
- ents != -EIO && ents != -EREMOTEIO))
+ } else if (WARN_ON_ONCE(ents != -EINVAL && ents != -ENOMEM &&
+ ents != -EIO && ents != -EREMOTEIO)) {
return -EIO;
+ }
return ents;
}
--- a/mm/kmsan/hooks.c~dma-kmsan-unpoison-dma-mappings
+++ a/mm/kmsan/hooks.c
@@ -10,9 +10,11 @@
*/
#include <linux/cacheflush.h>
+#include <linux/dma-direction.h>
#include <linux/gfp.h>
#include <linux/mm.h>
#include <linux/mm_types.h>
+#include <linux/scatterlist.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
@@ -242,6 +244,63 @@ void kmsan_copy_to_user(void __user *to,
}
EXPORT_SYMBOL(kmsan_copy_to_user);
+static void kmsan_handle_dma_page(const void *addr, size_t size,
+ enum dma_data_direction dir)
+{
+ switch (dir) {
+ case DMA_BIDIRECTIONAL:
+ kmsan_internal_check_memory((void *)addr, size, /*user_addr*/ 0,
+ REASON_ANY);
+ kmsan_internal_unpoison_memory((void *)addr, size,
+ /*checked*/ false);
+ break;
+ case DMA_TO_DEVICE:
+ kmsan_internal_check_memory((void *)addr, size, /*user_addr*/ 0,
+ REASON_ANY);
+ break;
+ case DMA_FROM_DEVICE:
+ kmsan_internal_unpoison_memory((void *)addr, size,
+ /*checked*/ false);
+ break;
+ case DMA_NONE:
+ break;
+ }
+}
+
+/* Helper function to handle DMA data transfers. */
+void kmsan_handle_dma(struct page *page, size_t offset, size_t size,
+ enum dma_data_direction dir)
+{
+ u64 page_offset, to_go, addr;
+
+ if (PageHighMem(page))
+ return;
+ addr = (u64)page_address(page) + offset;
+ /*
+ * The kernel may occasionally give us adjacent DMA pages not belonging
+ * to the same allocation. Process them separately to avoid triggering
+ * internal KMSAN checks.
+ */
+ while (size > 0) {
+ page_offset = addr % PAGE_SIZE;
+ to_go = min(PAGE_SIZE - page_offset, (u64)size);
+ kmsan_handle_dma_page((void *)addr, to_go, dir);
+ addr += to_go;
+ size -= to_go;
+ }
+}
+
+void kmsan_handle_dma_sg(struct scatterlist *sg, int nents,
+ enum dma_data_direction dir)
+{
+ struct scatterlist *item;
+ int i;
+
+ for_each_sg(sg, item, nents, i)
+ kmsan_handle_dma(sg_page(item), item->offset, item->length,
+ dir);
+}
+
/* Functions from kmsan-checks.h follow. */
void kmsan_poison_memory(const void *address, size_t size, gfp_t flags)
{
_
Patches currently in -mm which might be from glider@xxxxxxxxxx are
stackdepot-reserve-5-extra-bits-in-depot_stack_handle_t.patch
instrumentedh-allow-instrumenting-both-sides-of-copy_from_user.patch
x86-asm-instrument-usercopy-in-get_user-and-put_user.patch
asm-generic-instrument-usercopy-in-cacheflushh.patch
kmsan-add-rest-documentation.patch
kmsan-introduce-__no_sanitize_memory-and-__no_kmsan_checks.patch
kmsan-mark-noinstr-as-__no_sanitize_memory.patch
x86-kmsan-pgtable-reduce-vmalloc-space.patch
libnvdimm-pfn_dev-increase-max_struct_page_size.patch
kmsan-add-kmsan-runtime-core.patch
kmsan-disable-instrumentation-of-unsupported-common-kernel-code.patch
maintainers-add-entry-for-kmsan.patch
mm-kmsan-maintain-kmsan-metadata-for-page-operations.patch
mm-kmsan-call-kmsan-hooks-from-slub-code.patch
kmsan-handle-task-creation-and-exiting.patch
init-kmsan-call-kmsan-initialization-routines.patch
instrumentedh-add-kmsan-support.patch
kmsan-unpoison-tlb-in-arch_tlb_gather_mmu.patch
kmsan-add-iomap-support.patch
input-libps2-mark-data-received-in-__ps2_command-as-initialized.patch
dma-kmsan-unpoison-dma-mappings.patch
virtio-kmsan-check-unpoison-scatterlist-in-vring_map_one_sg.patch
kmsan-handle-memory-sent-to-from-usb.patch
kmsan-add-tests-for-kmsan.patch
kmsan-disable-strscpy-optimization-under-kmsan.patch
crypto-kmsan-disable-accelerated-configs-under-kmsan.patch
kmsan-disable-physical-page-merging-in-biovec.patch
block-kmsan-skip-bio-block-merging-logic-for-kmsan.patch
kcov-kmsan-unpoison-area-list-in-kcov_remote_area_put.patch
security-kmsan-fix-interoperability-with-auto-initialization.patch
objtool-kmsan-list-kmsan-api-functions-as-uaccess-safe.patch
x86-kmsan-disable-instrumentation-of-unsupported-code.patch
x86-kmsan-skip-shadow-checks-in-__switch_to.patch
x86-kmsan-handle-open-coded-assembly-in-lib-iomemc.patch
x86-kmsan-use-__msan_-string-functions-where-possible.patch
x86-kmsan-sync-metadata-pages-on-page-fault.patch
x86-kasan-kmsan-support-config_generic_csum-on-x86-enable-it-for-kasan-kmsan.patch
x86-fs-kmsan-disable-config_dcache_word_access.patch
x86-kmsan-dont-instrument-stack-walking-functions.patch
entry-kmsan-introduce-kmsan_unpoison_entry_regs.patch
bpf-kmsan-initialize-bpf-registers-with-zeroes.patch
mm-fs-initialize-fsdata-passed-to-write_begin-write_end-interface.patch
x86-kmsan-enable-kmsan-builds-for-x86.patch
