I'm a little concerned with how enabling/disabling works. If an
enable() is forgotten once, it's disabled forever. If disable() is
forgotten once, the toggle is reversed for the forseable future. MB
check for inequality in kasan_enabled()? like current->kasan_depth >=
0 (will need a signed int for the field). Do you think it's going to
decrease performance?
LGTM
On Mon, Nov 24, 2014 at 9:02 PM, Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx> wrote:
> Kernel Address sanitizer (KASan) is a dynamic memory error detector. It provides
> fast and comprehensive solution for finding use-after-free and out-of-bounds bugs.
>
> KASAN uses compile-time instrumentation for checking every memory access,
> therefore GCC >= v4.9.2 required.
>
> This patch only adds infrastructure for kernel address sanitizer. It's not
> available for use yet. The idea and some code was borrowed from [1].
>
> Basic idea:
> The main idea of KASAN is to use shadow memory to record whether each byte of memory
> is safe to access or not, and use compiler's instrumentation to check the shadow memory
> on each memory access.
>
> Address sanitizer uses 1/8 of the memory addressable in kernel for shadow memory
> and uses direct mapping with a scale and offset to translate a memory
> address to its corresponding shadow address.
>
> Here is function to translate address to corresponding shadow address:
>
> unsigned long kasan_mem_to_shadow(unsigned long addr)
> {
> return (addr >> KASAN_SHADOW_SCALE_SHIFT) + KASAN_SHADOW_OFFSET;
> }
> where KASAN_SHADOW_SCALE_SHIFT = 3.
>
> So for every 8 bytes there is one corresponding byte of shadow memory.
> The following encoding used for each shadow byte: 0 means that all 8 bytes of the
> corresponding memory region are valid for access; k (1 <= k <= 7) means that
> the first k bytes are valid for access, and other (8 - k) bytes are not;
> Any negative value indicates that the entire 8-bytes are inaccessible.
> Different negative values used to distinguish between different kinds of
> inaccessible memory (redzones, freed memory) (see mm/kasan/kasan.h).
>
> To be able to detect accesses to bad memory we need a special compiler.
> Such compiler inserts a specific function calls (__asan_load*(addr), __asan_store*(addr))
> before each memory access of size 1, 2, 4, 8 or 16.
>
> These functions check whether memory region is valid to access or not by checking
> corresponding shadow memory. If access is not valid an error printed.
>
> Historical background of the address sanitizer from Dmitry Vyukov <dvyukov@xxxxxxxxxx>:
> "We've developed the set of tools, AddressSanitizer (Asan),
> ThreadSanitizer and MemorySanitizer, for user space. We actively use
> them for testing inside of Google (continuous testing, fuzzing,
> running prod services). To date the tools have found more than 10'000
> scary bugs in Chromium, Google internal codebase and various
> open-source projects (Firefox, OpenSSL, gcc, clang, ffmpeg, MySQL and
> lots of others): [2] [3] [4].
> The tools are part of both gcc and clang compilers.
>
> We have not yet done massive testing under the Kernel AddressSanitizer
> (it's kind of chicken and egg problem, you need it to be upstream to
> start applying it extensively). To date it has found about 50 bugs.
> Bugs that we've found in upstream kernel are listed in [5].
> We've also found ~20 bugs in out internal version of the kernel. Also
> people from Samsung and Oracle have found some.
>
> [...]
>
> As others noted, the main feature of AddressSanitizer is its
> performance due to inline compiler instrumentation and simple linear
> shadow memory. User-space Asan has ~2x slowdown on computational
> programs and ~2x memory consumption increase. Taking into account that
> kernel usually consumes only small fraction of CPU and memory when
> running real user-space programs, I would expect that kernel Asan will
> have ~10-30% slowdown and similar memory consumption increase (when we
> finish all tuning).
>
> I agree that Asan can well replace kmemcheck. We have plans to start
> working on Kernel MemorySanitizer that finds uses of unitialized
> memory. Asan+Msan will provide feature-parity with kmemcheck. As
> others noted, Asan will unlikely replace debug slab and pagealloc that
> can be enabled at runtime. Asan uses compiler instrumentation, so even
> if it is disabled, it still incurs visible overheads.
>
> Asan technology is easily portable to other architectures. Compiler
> instrumentation is fully portable. Runtime has some arch-dependent
> parts like shadow mapping and atomic operation interception. They are
> relatively easy to port."
>
> Comparison with other debugging features:
> ========================================
>
> KMEMCHECK:
> - KASan can do almost everything that kmemcheck can. KASan uses compile-time
> instrumentation, which makes it significantly faster than kmemcheck.
> The only advantage of kmemcheck over KASan is detection of uninitialized
> memory reads.
>
> Some brief performance testing showed that kasan could be x500-x600 times
> faster than kmemcheck:
>
> $ netperf -l 30
> MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to localhost (127.0.0.1) port 0 AF_INET
> Recv Send Send
> Socket Socket Message Elapsed
> Size Size Size Time Throughput
> bytes bytes bytes secs. 10^6bits/sec
>
> no debug: 87380 16384 16384 30.00 41624.72
>
> kasan inline: 87380 16384 16384 30.00 12870.54
>
> kasan outline: 87380 16384 16384 30.00 10586.39
>
> kmemcheck: 87380 16384 16384 30.03 20.23
>
> - Also kmemcheck couldn't work on several CPUs. It always sets number of CPUs to 1.
> KASan doesn't have such limitation.
>
> DEBUG_PAGEALLOC:
> - KASan is slower than DEBUG_PAGEALLOC, but KASan works on sub-page
> granularity level, so it able to find more bugs.
>
> SLUB_DEBUG (poisoning, redzones):
> - SLUB_DEBUG has lower overhead than KASan.
>
> - SLUB_DEBUG in most cases are not able to detect bad reads,
> KASan able to detect both reads and writes.
>
> - In some cases (e.g. redzone overwritten) SLUB_DEBUG detect
> bugs only on allocation/freeing of object. KASan catch
> bugs right before it will happen, so we always know exact
> place of first bad read/write.
>
> [1] https://code.google.com/p/address-sanitizer/wiki/AddressSanitizerForKernel
> [2] https://code.google.com/p/address-sanitizer/wiki/FoundBugs
> [3] https://code.google.com/p/thread-sanitizer/wiki/FoundBugs
> [4] https://code.google.com/p/memory-sanitizer/wiki/FoundBugs
> [5] https://code.google.com/p/address-sanitizer/wiki/AddressSanitizerForKernel#Trophies
>
> Based on work by Andrey Konovalov <adech.fo@xxxxxxxxx>
>
> Signed-off-by: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx>
> ---
> Documentation/kasan.txt | 169 +++++++++++++++
> Makefile | 23 ++-
> drivers/firmware/efi/libstub/Makefile | 1 +
> include/linux/kasan.h | 42 ++++
> include/linux/sched.h | 3 +
> lib/Kconfig.debug | 2 +
> lib/Kconfig.kasan | 43 ++++
> mm/Makefile | 1 +
> mm/kasan/Makefile | 7 +
> mm/kasan/kasan.c | 374 ++++++++++++++++++++++++++++++++++
> mm/kasan/kasan.h | 49 +++++
> mm/kasan/report.c | 205 +++++++++++++++++++
> scripts/Makefile.lib | 10 +
> 13 files changed, 927 insertions(+), 2 deletions(-)
> create mode 100644 Documentation/kasan.txt
> create mode 100644 include/linux/kasan.h
> create mode 100644 lib/Kconfig.kasan
> create mode 100644 mm/kasan/Makefile
> create mode 100644 mm/kasan/kasan.c
> create mode 100644 mm/kasan/kasan.h
> create mode 100644 mm/kasan/report.c
>
> diff --git a/Documentation/kasan.txt b/Documentation/kasan.txt
> new file mode 100644
> index 0000000..a3a9009
> --- /dev/null
> +++ b/Documentation/kasan.txt
> @@ -0,0 +1,169 @@
> +Kernel address sanitizer
> +================
> +
> +0. Overview
> +===========
> +
> +Kernel Address sanitizer (KASan) is a dynamic memory error detector. It provides
> +a fast and comprehensive solution for finding use-after-free and out-of-bounds
> +bugs.
> +
> +KASan uses compile-time instrumentation for checking every memory access,
> +therefore you will need a certain version of GCC >= 4.9.2
> +
> +Currently KASan is supported only for x86_64 architecture and requires that the
> +kernel be built with the SLUB allocator.
> +
> +1. Usage
> +=========
> +
> +To enable KASAN configure kernel with:
> +
> + CONFIG_KASAN = y
> +
> +and choose between CONFIG_KASAN_OUTLINE and CONFIG_KASAN_INLINE. Outline/inline
> +is compiler instrumentation types. The former produces smaller binary the
> +latter is 1.1 - 2 times faster. Inline instrumentation requires GCC 5.0 or
> +latter.
> +
> +Currently KASAN works only with the SLUB memory allocator.
> +For better bug detection and nicer report, enable CONFIG_STACKTRACE and put
> +at least 'slub_debug=U' in the boot cmdline.
> +
> +To disable instrumentation for specific files or directories, add a line
> +similar to the following to the respective kernel Makefile:
> +
> + For a single file (e.g. main.o):
> + KASAN_SANITIZE_main.o := n
> +
> + For all files in one directory:
> + KASAN_SANITIZE := n
> +
> +1.1 Error reports
> +==========
> +
> +A typical out of bounds access report looks like this:
> +
> +==================================================================
> +BUG: AddressSanitizer: out of bounds access in kmalloc_oob_right+0x65/0x75 [test_kasan] at addr ffff8800693bc5d3
> +Write of size 1 by task modprobe/1689
> +=============================================================================
> +BUG kmalloc-128 (Not tainted): kasan error
> +-----------------------------------------------------------------------------
> +
> +Disabling lock debugging due to kernel taint
> +INFO: Allocated in kmalloc_oob_right+0x3d/0x75 [test_kasan] age=0 cpu=0 pid=1689
> + __slab_alloc+0x4b4/0x4f0
> + kmem_cache_alloc_trace+0x10b/0x190
> + kmalloc_oob_right+0x3d/0x75 [test_kasan]
> + init_module+0x9/0x47 [test_kasan]
> + do_one_initcall+0x99/0x200
> + load_module+0x2cb3/0x3b20
> + SyS_finit_module+0x76/0x80
> + system_call_fastpath+0x12/0x17
> +INFO: Slab 0xffffea0001a4ef00 objects=17 used=7 fp=0xffff8800693bd728 flags=0x100000000004080
> +INFO: Object 0xffff8800693bc558 @offset=1368 fp=0xffff8800693bc720
> +
> +Bytes b4 ffff8800693bc548: 00 00 00 00 00 00 00 00 5a 5a 5a 5a 5a 5a 5a 5a ........ZZZZZZZZ
> +Object ffff8800693bc558: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
> +Object ffff8800693bc568: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
> +Object ffff8800693bc578: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
> +Object ffff8800693bc588: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
> +Object ffff8800693bc598: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
> +Object ffff8800693bc5a8: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
> +Object ffff8800693bc5b8: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
> +Object ffff8800693bc5c8: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5 kkkkkkkkkkkkkkk.
> +Redzone ffff8800693bc5d8: cc cc cc cc cc cc cc cc ........
> +Padding ffff8800693bc718: 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZ
> +CPU: 0 PID: 1689 Comm: modprobe Tainted: G B 3.18.0-rc1-mm1+ #98
> +Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5-0-ge51488c-20140602_164612-nilsson.home.kraxel.org 04/01/2014
> + ffff8800693bc000 0000000000000000 ffff8800693bc558 ffff88006923bb78
> + ffffffff81cc68ae 00000000000000f3 ffff88006d407600 ffff88006923bba8
> + ffffffff811fd848 ffff88006d407600 ffffea0001a4ef00 ffff8800693bc558
> +Call Trace:
> + [<ffffffff81cc68ae>] dump_stack+0x46/0x58
> + [<ffffffff811fd848>] print_trailer+0xf8/0x160
> + [<ffffffffa00026a7>] ? kmem_cache_oob+0xc3/0xc3 [test_kasan]
> + [<ffffffff811ff0f5>] object_err+0x35/0x40
> + [<ffffffffa0002065>] ? kmalloc_oob_right+0x65/0x75 [test_kasan]
> + [<ffffffff8120b9fa>] kasan_report_error+0x38a/0x3f0
> + [<ffffffff8120a79f>] ? kasan_poison_shadow+0x2f/0x40
> + [<ffffffff8120b344>] ? kasan_unpoison_shadow+0x14/0x40
> + [<ffffffff8120a79f>] ? kasan_poison_shadow+0x2f/0x40
> + [<ffffffffa00026a7>] ? kmem_cache_oob+0xc3/0xc3 [test_kasan]
> + [<ffffffff8120a995>] __asan_store1+0x75/0xb0
> + [<ffffffffa0002601>] ? kmem_cache_oob+0x1d/0xc3 [test_kasan]
> + [<ffffffffa0002065>] ? kmalloc_oob_right+0x65/0x75 [test_kasan]
> + [<ffffffffa0002065>] kmalloc_oob_right+0x65/0x75 [test_kasan]
> + [<ffffffffa00026b0>] init_module+0x9/0x47 [test_kasan]
> + [<ffffffff810002d9>] do_one_initcall+0x99/0x200
> + [<ffffffff811e4e5c>] ? __vunmap+0xec/0x160
> + [<ffffffff81114f63>] load_module+0x2cb3/0x3b20
> + [<ffffffff8110fd70>] ? m_show+0x240/0x240
> + [<ffffffff81115f06>] SyS_finit_module+0x76/0x80
> + [<ffffffff81cd3129>] system_call_fastpath+0x12/0x17
> +Memory state around the buggy address:
> + ffff8800693bc300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> + ffff8800693bc380: fc fc 00 00 00 00 00 00 00 00 00 00 00 00 00 fc
> + ffff8800693bc400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> + ffff8800693bc480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> + ffff8800693bc500: fc fc fc fc fc fc fc fc fc fc fc 00 00 00 00 00
> +>ffff8800693bc580: 00 00 00 00 00 00 00 00 00 00 03 fc fc fc fc fc
> + ^
> + ffff8800693bc600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> + ffff8800693bc680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> + ffff8800693bc700: fc fc fc fc fb fb fb fb fb fb fb fb fb fb fb fb
> + ffff8800693bc780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> + ffff8800693bc800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> +==================================================================
> +
> +First sections describe slub object where bad access happened.
> +See 'SLUB Debug output' section in Documentation/vm/slub.txt for details.
> +
> +In the last section the report shows memory state around the accessed address.
> +Reading this part requires some more understanding of how KASAN works.
> +
> +Each 8 bytes of memory are encoded in one shadow byte as accessible,
> +partially accessible, freed or they can be part of a redzone.
> +We use the following encoding for each shadow byte: 0 means that all 8 bytes
> +of the corresponding memory region are accessible; number N (1 <= N <= 7) means
> +that the first N bytes are accessible, and other (8 - N) bytes are not;
> +any negative value indicates that the entire 8-byte word is inaccessible.
> +We use different negative values to distinguish between different kinds of
> +inaccessible memory like redzones or freed memory (see mm/kasan/kasan.h).
> +
> +In the report above the arrows point to the shadow byte 03, which means that
> +the accessed address is partially accessible.
> +
> +
> +2. Implementation details
> +========================
> +
> +From a high level, our approach to memory error detection is similar to that
> +of kmemcheck: use shadow memory to record whether each byte of memory is safe
> +to access, and use compile-time instrumentation to check shadow memory on each
> +memory access.
> +
> +AddressSanitizer dedicates 1/8 of kernel memory to its shadow memory
> +(e.g. 16TB to cover 128TB on x86_64) and uses direct mapping with a scale and
> +offset to translate a memory address to its corresponding shadow address.
> +
> +Here is the function witch translate an address to its corresponding shadow
> +address:
> +
> +unsigned long kasan_mem_to_shadow(unsigned long addr)
> +{
> + return (addr >> KASAN_SHADOW_SCALE_SHIFT) + KASAN_SHADOW_OFFSET;
> +}
> +
> +where KASAN_SHADOW_SCALE_SHIFT = 3.
> +
> +Compile-time instrumentation used for checking memory accesses. Compiler inserts
> +function calls (__asan_load*(addr), __asan_store*(addr)) before each memory
> +access of size 1, 2, 4, 8 or 16. These functions check whether memory access is
> +valid or not by checking corresponding shadow memory.
> +
> +GCC 5.0 has possibility to perform inline instrumentation. Instead of making
> +function calls GCC directly inserts the code to check the shadow memory.
> +This option significantly enlarges kernel but it gives x1.1-x2 performance
> +boost over outline instrumented kernel.
> diff --git a/Makefile b/Makefile
> index 92edae4..052c1f4 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -382,7 +382,7 @@ LDFLAGS_MODULE =
> CFLAGS_KERNEL =
> AFLAGS_KERNEL =
> CFLAGS_GCOV = -fprofile-arcs -ftest-coverage
> -
> +CFLAGS_KASAN = $(call cc-option, -fsanitize=kernel-address)
>
> # Use USERINCLUDE when you must reference the UAPI directories only.
> USERINCLUDE := \
> @@ -427,7 +427,7 @@ export MAKE AWK GENKSYMS INSTALLKERNEL PERL PYTHON UTS_MACHINE
> export HOSTCXX HOSTCXXFLAGS LDFLAGS_MODULE CHECK CHECKFLAGS
>
> export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS LDFLAGS
> -export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE CFLAGS_GCOV
> +export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE CFLAGS_GCOV CFLAGS_KASAN
> export KBUILD_AFLAGS AFLAGS_KERNEL AFLAGS_MODULE
> export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_LDFLAGS_MODULE
> export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL
> @@ -758,6 +758,25 @@ ifdef CONFIG_DEBUG_SECTION_MISMATCH
> KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once)
> endif
>
> +ifdef CONFIG_KASAN
> +ifdef CONFIG_KASAN_INLINE
> + kasan_inline := $(call cc-option, $(CFLAGS_KASAN) \
> + -fasan-shadow-offset=$(CONFIG_KASAN_SHADOW_OFFSET) \
> + --param asan-instrumentation-with-call-threshold=10000)
> + ifeq ($(kasan_inline),)
> + $(warning Cannot use CONFIG_KASAN_INLINE: \
> + inline instrumentation is not supported by compiler. Trying CONFIG_KASAN_OUTLINE.)
> + else
> + CFLAGS_KASAN := $(kasan_inline)
> + endif
> +
> +endif
> + ifeq ($(CFLAGS_KASAN),)
> + $(warning Cannot use CONFIG_KASAN: \
> + -fsanitize=kernel-address is not supported by compiler)
> + endif
> +endif
> +
> # arch Makefile may override CC so keep this after arch Makefile is included
> NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
> CHECKFLAGS += $(NOSTDINC_FLAGS)
> diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
> index b14bc2b..c5533c7 100644
> --- a/drivers/firmware/efi/libstub/Makefile
> +++ b/drivers/firmware/efi/libstub/Makefile
> @@ -19,6 +19,7 @@ KBUILD_CFLAGS := $(cflags-y) \
> $(call cc-option,-fno-stack-protector)
>
> GCOV_PROFILE := n
> +KASAN_SANITIZE := n
>
> lib-y := efi-stub-helper.o
> lib-$(CONFIG_EFI_ARMSTUB) += arm-stub.o fdt.o
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> new file mode 100644
> index 0000000..01c99fe
> --- /dev/null
> +++ b/include/linux/kasan.h
> @@ -0,0 +1,42 @@
> +#ifndef _LINUX_KASAN_H
> +#define _LINUX_KASAN_H
> +
> +#include <linux/types.h>
> +
> +struct kmem_cache;
> +struct page;
> +
> +#ifdef CONFIG_KASAN
> +#include <asm/kasan.h>
> +#include <linux/sched.h>
> +
> +#define KASAN_SHADOW_SCALE_SHIFT 3
> +#define KASAN_SHADOW_OFFSET _AC(CONFIG_KASAN_SHADOW_OFFSET, UL)
> +
> +static inline unsigned long kasan_mem_to_shadow(unsigned long addr)
> +{
> + return (addr >> KASAN_SHADOW_SCALE_SHIFT) + KASAN_SHADOW_OFFSET;
> +}
> +
> +static inline void kasan_enable_local(void)
> +{
> + current->kasan_depth++;
> +}
> +
> +static inline void kasan_disable_local(void)
> +{
> + current->kasan_depth--;
> +}
> +
> +void kasan_unpoison_shadow(const void *address, size_t size);
> +
> +#else /* CONFIG_KASAN */
> +
> +static inline void kasan_unpoison_shadow(const void *address, size_t size) {}
> +
> +static inline void kasan_enable_local(void) {}
> +static inline void kasan_disable_local(void) {}
> +
> +#endif /* CONFIG_KASAN */
> +
> +#endif /* LINUX_KASAN_H */
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 8db31ef..26e1b47 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -1662,6 +1662,9 @@ struct task_struct {
> unsigned long timer_slack_ns;
> unsigned long default_timer_slack_ns;
>
> +#ifdef CONFIG_KASAN
> + unsigned int kasan_depth;
> +#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 ddd070a..bb26ec3 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -666,6 +666,8 @@ config DEBUG_STACKOVERFLOW
>
> source "lib/Kconfig.kmemcheck"
>
> +source "lib/Kconfig.kasan"
> +
> endmenu # "Memory Debugging"
>
> config DEBUG_SHIRQ
> diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
> new file mode 100644
> index 0000000..10341df
> --- /dev/null
> +++ b/lib/Kconfig.kasan
> @@ -0,0 +1,43 @@
> +config HAVE_ARCH_KASAN
> + bool
> +
> +if HAVE_ARCH_KASAN
> +
> +config KASAN
> + bool "AddressSanitizer: runtime memory debugger"
> + help
> + Enables address sanitizer - runtime memory debugger,
> + designed to find out-of-bounds accesses and use-after-free bugs.
> + This is strictly debugging feature. It consumes about 1/8
> + of available memory and brings about ~x3 performance slowdown.
> + For better error detection enable CONFIG_STACKTRACE,
> + and add slub_debug=U to boot cmdline.
> +
> +config KASAN_SHADOW_OFFSET
> + hex
> +
> +choice
> + prompt "Instrumentation type"
> + depends on KASAN
> + default KASAN_OUTLINE
> +
> +config KASAN_OUTLINE
> + bool "Outline instrumentation"
> + help
> + Before every memory access compiler insert function call
> + __asan_load*/__asan_store*. These functions performs check
> + of shadow memory. This is slower than inline instrumentation,
> + however it doesn't bloat size of kernel's .text section so
> + much as inline does.
> +
> +config KASAN_INLINE
> + bool "Inline instrumentation"
> + help
> + Compiler directly inserts code checking shadow memory before
> + memory accesses. This is faster than outline (in some workloads
> + it gives about x2 boost over outline instrumentation), but
> + make kernel's .text size much bigger.
> +
> +endchoice
> +
> +endif
> diff --git a/mm/Makefile b/mm/Makefile
> index d9d5794..33d9971 100644
> --- a/mm/Makefile
> +++ b/mm/Makefile
> @@ -72,3 +72,4 @@ obj-$(CONFIG_ZSMALLOC) += zsmalloc.o
> obj-$(CONFIG_GENERIC_EARLY_IOREMAP) += early_ioremap.o
> obj-$(CONFIG_CMA) += cma.o
> obj-$(CONFIG_MEMORY_BALLOON) += balloon_compaction.o
> +obj-$(CONFIG_KASAN) += kasan/
> diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile
> new file mode 100644
> index 0000000..ef2d313
> --- /dev/null
> +++ b/mm/kasan/Makefile
> @@ -0,0 +1,7 @@
> +KASAN_SANITIZE := n
> +
> +# Function splitter causes unnecessary splits in __asan_load1/__asan_store1
> +# see: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63533
> +CFLAGS_kasan.o := $(call cc-option, -fno-conserve-stack)
> +
> +obj-y := kasan.o report.o
> diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
> new file mode 100644
> index 0000000..f77be01
> --- /dev/null
> +++ b/mm/kasan/kasan.c
> @@ -0,0 +1,374 @@
> +/*
> + * This file contains shadow memory manipulation code.
> + *
> + * Copyright (c) 2014 Samsung Electronics Co., Ltd.
> + * Author: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx>
> + *
> + * Some of code borrowed from https://github.com/xairy/linux by
> + * Andrey Konovalov <adech.fo@xxxxxxxxx>
> + *
> + * 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.
> + *
> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +#define DISABLE_BRANCH_PROFILING
> +
> +#include <linux/export.h>
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/memblock.h>
> +#include <linux/mm.h>
> +#include <linux/printk.h>
> +#include <linux/sched.h>
> +#include <linux/slab.h>
> +#include <linux/stacktrace.h>
> +#include <linux/string.h>
> +#include <linux/types.h>
> +#include <linux/kasan.h>
> +
> +#include "kasan.h"
> +
> +/*
> + * Poisons the shadow memory for 'size' bytes starting from 'addr'.
> + * Memory addresses should be aligned to KASAN_SHADOW_SCALE_SIZE.
> + */
> +static void kasan_poison_shadow(const void *address, size_t size, u8 value)
> +{
> + unsigned long shadow_start, shadow_end;
> + unsigned long addr = (unsigned long)address;
> +
> + shadow_start = kasan_mem_to_shadow(addr);
> + shadow_end = kasan_mem_to_shadow(addr + size);
> +
> + memset((void *)shadow_start, value, shadow_end - shadow_start);
> +}
> +
> +void kasan_unpoison_shadow(const void *address, size_t size)
> +{
> + kasan_poison_shadow(address, size, 0);
> +
> + if (size & KASAN_SHADOW_MASK) {
> + u8 *shadow = (u8 *)kasan_mem_to_shadow((unsigned long)address
> + + size);
> + *shadow = size & KASAN_SHADOW_MASK;
> + }
> +}
> +
> +static __always_inline bool memory_is_poisoned_1(unsigned long addr)
> +{
> + s8 shadow_value = *(s8 *)kasan_mem_to_shadow(addr);
> +
> + if (unlikely(shadow_value)) {
> + s8 last_accessible_byte = addr & KASAN_SHADOW_MASK;
> + return unlikely(last_accessible_byte >= shadow_value);
> + }
> +
> + return false;
> +}
> +
> +static __always_inline bool memory_is_poisoned_2(unsigned long addr)
> +{
> + u16 *shadow_addr = (u16 *)kasan_mem_to_shadow(addr);
> +
> + if (unlikely(*shadow_addr)) {
> + if (memory_is_poisoned_1(addr + 1))
> + return true;
> +
> + if (likely(((addr + 1) & KASAN_SHADOW_MASK) != 0))
> + return false;
> +
> + return unlikely(*(u8 *)shadow_addr);
> + }
> +
> + return false;
> +}
> +
> +static __always_inline bool memory_is_poisoned_4(unsigned long addr)
> +{
> + u16 *shadow_addr = (u16 *)kasan_mem_to_shadow(addr);
> +
> + if (unlikely(*shadow_addr)) {
> + if (memory_is_poisoned_1(addr + 3))
> + return true;
> +
> + if (likely(((addr + 3) & KASAN_SHADOW_MASK) >= 3))
> + return false;
> +
> + return unlikely(*(u8 *)shadow_addr);
> + }
> +
> + return false;
> +}
> +
> +static __always_inline bool memory_is_poisoned_8(unsigned long addr)
> +{
> + u16 *shadow_addr = (u16 *)kasan_mem_to_shadow(addr);
> +
> + if (unlikely(*shadow_addr)) {
> + if (memory_is_poisoned_1(addr + 7))
> + return true;
> +
> + if (likely(((addr + 7) & KASAN_SHADOW_MASK) >= 7))
> + return false;
> +
> + return unlikely(*(u8 *)shadow_addr);
> + }
> +
> + return false;
> +}
> +
> +static __always_inline bool memory_is_poisoned_16(unsigned long addr)
> +{
> + u32 *shadow_addr = (u32 *)kasan_mem_to_shadow(addr);
> +
> + if (unlikely(*shadow_addr)) {
> + u16 shadow_first_bytes = *(u16 *)shadow_addr;
> + s8 last_byte = (addr + 15) & KASAN_SHADOW_MASK;
> +
> + if (unlikely(shadow_first_bytes))
> + return true;
> +
> + if (likely(!last_byte))
> + return false;
> +
> + return memory_is_poisoned_1(addr + 15);
> + }
> +
> + return false;
> +}
> +
> +static __always_inline unsigned long bytes_is_zero(unsigned long start,
> + size_t size)
> +{
> + while (size) {
> + if (unlikely(*(u8 *)start))
> + return start;
> + start++;
> + size--;
> + }
> +
> + return 0;
> +}
> +
> +static __always_inline unsigned long memory_is_zero(unsigned long start,
> + unsigned long end)
> +{
> + unsigned int prefix = start % 8;
> + unsigned int words;
> + unsigned long ret;
> +
> + if (end - start <= 16)
> + return bytes_is_zero(start, end - start);
> +
> + if (prefix) {
> + prefix = 8 - prefix;
> + ret = bytes_is_zero(start, prefix);
> + if (unlikely(ret))
> + return ret;
> + start += prefix;
> + }
> +
> + words = (end - start) / 8;
> + while (words) {
> + if (unlikely(*(u64 *)start))
> + return bytes_is_zero(start, 8);
> + start += 8;
> + words--;
> + }
> +
> + return bytes_is_zero(start, (end - start) % 8);
> +}
> +
> +static __always_inline bool memory_is_poisoned_n(unsigned long addr,
> + size_t size)
> +{
> + unsigned long ret;
> +
> + ret = memory_is_zero(kasan_mem_to_shadow(addr),
> + kasan_mem_to_shadow(addr + size - 1) + 1);
> +
> + if (unlikely(ret)) {
> + unsigned long last_byte = addr + size - 1;
> + s8 *last_shadow = (s8 *)kasan_mem_to_shadow(last_byte);
> +
> + if (unlikely(ret != (unsigned long)last_shadow ||
> + ((last_byte & KASAN_SHADOW_MASK) >= *last_shadow)))
> + return true;
> + }
> + return false;
> +}
> +
> +static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size)
> +{
> + if (__builtin_constant_p(size)) {
> + switch (size) {
> + case 1:
> + return memory_is_poisoned_1(addr);
> + case 2:
> + return memory_is_poisoned_2(addr);
> + case 4:
> + return memory_is_poisoned_4(addr);
> + case 8:
> + return memory_is_poisoned_8(addr);
> + case 16:
> + return memory_is_poisoned_16(addr);
> + default:
> + BUILD_BUG();
> + }
> + }
> +
> + return memory_is_poisoned_n(addr, size);
> +}
> +
> +
> +static __always_inline void check_memory_region(unsigned long addr,
> + size_t size, bool write)
> +{
> + struct access_info info;
> +
> + if (unlikely(size == 0))
> + return;
> +
> + if (unlikely(addr < kasan_shadow_to_mem(KASAN_SHADOW_START))) {
> + info.access_addr = addr;
> + info.access_size = size;
> + info.is_write = write;
> + info.ip = _RET_IP_;
> + kasan_report_user_access(&info);
> + return;
> + }
> +
> + if (likely(!memory_is_poisoned(addr, size)))
> + return;
> +
> + kasan_report(addr, size, write);
> +}
> +
> +void __asan_load1(unsigned long addr)
> +{
> + check_memory_region(addr, 1, false);
> +}
> +EXPORT_SYMBOL(__asan_load1);
> +
> +void __asan_load2(unsigned long addr)
> +{
> + check_memory_region(addr, 2, false);
> +}
> +EXPORT_SYMBOL(__asan_load2);
> +
> +void __asan_load4(unsigned long addr)
> +{
> + check_memory_region(addr, 4, false);
> +}
> +EXPORT_SYMBOL(__asan_load4);
> +
> +void __asan_load8(unsigned long addr)
> +{
> + check_memory_region(addr, 8, false);
> +}
> +EXPORT_SYMBOL(__asan_load8);
> +
> +void __asan_load16(unsigned long addr)
> +{
> + check_memory_region(addr, 16, false);
> +}
> +EXPORT_SYMBOL(__asan_load16);
> +
> +void __asan_loadN(unsigned long addr, size_t size)
> +{
> + check_memory_region(addr, size, false);
> +}
> +EXPORT_SYMBOL(__asan_loadN);
> +
> +void __asan_store1(unsigned long addr)
> +{
> + check_memory_region(addr, 1, true);
> +}
> +EXPORT_SYMBOL(__asan_store1);
> +
> +void __asan_store2(unsigned long addr)
> +{
> + check_memory_region(addr, 2, true);
> +}
> +EXPORT_SYMBOL(__asan_store2);
> +
> +void __asan_store4(unsigned long addr)
> +{
> + check_memory_region(addr, 4, true);
> +}
> +EXPORT_SYMBOL(__asan_store4);
> +
> +void __asan_store8(unsigned long addr)
> +{
> + check_memory_region(addr, 8, true);
> +}
> +EXPORT_SYMBOL(__asan_store8);
> +
> +void __asan_store16(unsigned long addr)
> +{
> + check_memory_region(addr, 16, true);
> +}
> +EXPORT_SYMBOL(__asan_store16);
> +
> +void __asan_storeN(unsigned long addr, size_t size)
> +{
> + check_memory_region(addr, size, true);
> +}
> +EXPORT_SYMBOL(__asan_storeN);
> +
> +/* to shut up compiler complaints */
> +void __asan_handle_no_return(void) {}
> +EXPORT_SYMBOL(__asan_handle_no_return);
> +
> +
> +/* GCC 5.0 has different function names by default */
> +__attribute__((alias("__asan_load1")))
> +void __asan_load1_noabort(unsigned long);
> +EXPORT_SYMBOL(__asan_load1_noabort);
> +
> +__attribute__((alias("__asan_load2")))
> +void __asan_load2_noabort(unsigned long);
> +EXPORT_SYMBOL(__asan_load2_noabort);
> +
> +__attribute__((alias("__asan_load4")))
> +void __asan_load4_noabort(unsigned long);
> +EXPORT_SYMBOL(__asan_load4_noabort);
> +
> +__attribute__((alias("__asan_load8")))
> +void __asan_load8_noabort(unsigned long);
> +EXPORT_SYMBOL(__asan_load8_noabort);
> +
> +__attribute__((alias("__asan_load16")))
> +void __asan_load16_noabort(unsigned long);
> +EXPORT_SYMBOL(__asan_load16_noabort);
> +
> +__attribute__((alias("__asan_loadN")))
> +void __asan_loadN_noabort(unsigned long);
> +EXPORT_SYMBOL(__asan_loadN_noabort);
> +
> +__attribute__((alias("__asan_store1")))
> +void __asan_store1_noabort(unsigned long);
> +EXPORT_SYMBOL(__asan_store1_noabort);
> +
> +__attribute__((alias("__asan_store2")))
> +void __asan_store2_noabort(unsigned long);
> +EXPORT_SYMBOL(__asan_store2_noabort);
> +
> +__attribute__((alias("__asan_store4")))
> +void __asan_store4_noabort(unsigned long);
> +EXPORT_SYMBOL(__asan_store4_noabort);
> +
> +__attribute__((alias("__asan_store8")))
> +void __asan_store8_noabort(unsigned long);
> +EXPORT_SYMBOL(__asan_store8_noabort);
> +
> +__attribute__((alias("__asan_store16")))
> +void __asan_store16_noabort(unsigned long);
> +EXPORT_SYMBOL(__asan_store16_noabort);
> +
> +__attribute__((alias("__asan_storeN")))
> +void __asan_storeN_noabort(unsigned long);
> +EXPORT_SYMBOL(__asan_storeN_noabort);
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> new file mode 100644
> index 0000000..6da1d78
> --- /dev/null
> +++ b/mm/kasan/kasan.h
> @@ -0,0 +1,49 @@
> +#ifndef __MM_KASAN_KASAN_H
> +#define __MM_KASAN_KASAN_H
> +
> +#include <linux/kasan.h>
> +
> +#define KASAN_SHADOW_SCALE_SIZE (1UL << KASAN_SHADOW_SCALE_SHIFT)
> +#define KASAN_SHADOW_MASK (KASAN_SHADOW_SCALE_SIZE - 1)
> +
> +#define KASAN_SHADOW_GAP 0xF9 /* address belongs to shadow memory */
> +
> +struct access_info {
> + unsigned long access_addr;
> + unsigned long first_bad_addr;
> + size_t access_size;
> + bool is_write;
> + unsigned long ip;
> +};
> +
> +void kasan_report_error(struct access_info *info);
> +void kasan_report_user_access(struct access_info *info);
> +
> +static inline unsigned long kasan_shadow_to_mem(unsigned long shadow_addr)
> +{
> + return (shadow_addr - KASAN_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT;
> +}
> +
> +static inline bool kasan_enabled(void)
> +{
> + return !current->kasan_depth;
> +}
> +
> +static __always_inline void kasan_report(unsigned long addr,
> + size_t size,
> + bool is_write)
> +{
> + struct access_info info;
> +
> + if (likely(!kasan_enabled()))
> + return;
> +
> + info.access_addr = addr;
> + info.access_size = size;
> + info.is_write = is_write;
> + info.ip = _RET_IP_;
> + kasan_report_error(&info);
> +}
> +
> +
> +#endif
> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> new file mode 100644
> index 0000000..56a2089
> --- /dev/null
> +++ b/mm/kasan/report.c
> @@ -0,0 +1,205 @@
> +/*
> + * This file contains error reporting code.
> + *
> + * Copyright (c) 2014 Samsung Electronics Co., Ltd.
> + * Author: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx>
> + *
> + * Some of code borrowed from https://github.com/xairy/linux by
> + * Andrey Konovalov <adech.fo@xxxxxxxxx>
> + *
> + * 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/kernel.h>
> +#include <linux/mm.h>
> +#include <linux/printk.h>
> +#include <linux/sched.h>
> +#include <linux/slab.h>
> +#include <linux/stacktrace.h>
> +#include <linux/string.h>
> +#include <linux/types.h>
> +#include <linux/kasan.h>
> +
> +#include "kasan.h"
> +
> +/* Shadow layout customization. */
> +#define SHADOW_BYTES_PER_BLOCK 1
> +#define SHADOW_BLOCKS_PER_ROW 16
> +#define SHADOW_BYTES_PER_ROW (SHADOW_BLOCKS_PER_ROW * SHADOW_BYTES_PER_BLOCK)
> +#define SHADOW_ROWS_AROUND_ADDR 5
> +
> +static unsigned long find_first_bad_addr(unsigned long addr, size_t size)
> +{
> + u8 shadow_val = *(u8 *)kasan_mem_to_shadow(addr);
> + unsigned long first_bad_addr = addr;
> +
> + while (!shadow_val && first_bad_addr < addr + size) {
> + first_bad_addr += KASAN_SHADOW_SCALE_SIZE;
> + shadow_val = *(u8 *)kasan_mem_to_shadow(first_bad_addr);
> + }
> + return first_bad_addr;
> +}
> +
> +static void print_error_description(struct access_info *info)
> +{
> + const char *bug_type = "unknown crash";
> + u8 shadow_val;
> +
> + info->first_bad_addr = find_first_bad_addr(info->access_addr,
> + info->access_size);
> +
> + shadow_val = *(u8 *)kasan_mem_to_shadow(info->first_bad_addr);
> +
> + switch (shadow_val) {
> + case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
> + bug_type = "out of bounds access";
> + break;
> + case KASAN_SHADOW_GAP:
> + bug_type = "wild memory access";
> + break;
> + }
> +
> + pr_err("BUG: AddressSanitizer: %s in %pS at addr %p\n",
> + bug_type, (void *)info->ip,
> + (void *)info->access_addr);
> + pr_err("%s of size %zu by task %s/%d\n",
> + info->is_write ? "Write" : "Read",
> + info->access_size, current->comm, task_pid_nr(current));
> +}
> +
> +static void print_address_description(struct access_info *info)
> +{
> + struct page *page;
> + u8 shadow_val = *(u8 *)kasan_mem_to_shadow(info->first_bad_addr);
> +
> + page = virt_to_head_page((void *)info->access_addr);
> +
> + switch (shadow_val) {
> + case KASAN_SHADOW_GAP:
> + pr_err("No metainfo is available for this access.\n");
> + dump_stack();
> + break;
> + default:
> + WARN_ON(1);
> + }
> +}
> +
> +static bool row_is_guilty(unsigned long row, unsigned long guilty)
> +{
> + return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW);
> +}
> +
> +static int shadow_pointer_offset(unsigned long row, unsigned long shadow)
> +{
> + /* The length of ">ff00ff00ff00ff00: " is
> + * 3 + (BITS_PER_LONG/8)*2 chars.
> + */
> + return 3 + (BITS_PER_LONG/8)*2 + (shadow - row)*2 +
> + (shadow - row) / SHADOW_BYTES_PER_BLOCK + 1;
> +}
> +
> +static void print_shadow_for_address(unsigned long addr)
> +{
> + int i;
> + unsigned long shadow = kasan_mem_to_shadow(addr);
> + unsigned long aligned_shadow = round_down(shadow, SHADOW_BYTES_PER_ROW)
> + - SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW;
> +
> + pr_err("Memory state around the buggy address:\n");
> +
> + for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) {
> + unsigned long kaddr = kasan_shadow_to_mem(aligned_shadow);
> + char buffer[4 + (BITS_PER_LONG/8)*2];
> +
> + snprintf(buffer, sizeof(buffer),
> + (i == 0) ? ">%lx: " : " %lx: ", kaddr);
> +
> + kasan_disable_local();
> + print_hex_dump(KERN_ERR, buffer,
> + DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1,
> + (void *)aligned_shadow, SHADOW_BYTES_PER_ROW, 0);
> + kasan_enable_local();
> +
> + if (row_is_guilty(aligned_shadow, shadow))
> + pr_err("%*c\n",
> + shadow_pointer_offset(aligned_shadow, shadow),
> + '^');
> +
> + aligned_shadow += SHADOW_BYTES_PER_ROW;
> + }
> +}
> +
> +static DEFINE_SPINLOCK(report_lock);
> +
> +void kasan_report_error(struct access_info *info)
> +{
> + unsigned long flags;
> +
> + spin_lock_irqsave(&report_lock, flags);
> + pr_err("================================="
> + "=================================\n");
> + print_error_description(info);
> + print_address_description(info);
> + print_shadow_for_address(info->first_bad_addr);
> + pr_err("================================="
> + "=================================\n");
> + spin_unlock_irqrestore(&report_lock, flags);
> +}
> +
> +void kasan_report_user_access(struct access_info *info)
> +{
> + unsigned long flags;
> +
> + spin_lock_irqsave(&report_lock, flags);
> + pr_err("================================="
> + "=================================\n");
> + pr_err("BUG: AddressSanitizer: user-memory-access on address %lx\n",
> + info->access_addr);
> + pr_err("%s of size %zu by thread T%d:\n",
> + info->is_write ? "Write" : "Read",
> + info->access_size, current->pid);
> + dump_stack();
> + pr_err("================================="
> + "=================================\n");
> + spin_unlock_irqrestore(&report_lock, flags);
> +}
> +
> +#define DEFINE_ASAN_REPORT_LOAD(size) \
> +void __asan_report_load##size##_noabort(unsigned long addr) \
> +{ \
> + kasan_report(addr, size, false); \
> +} \
> +EXPORT_SYMBOL(__asan_report_load##size##_noabort)
> +
> +#define DEFINE_ASAN_REPORT_STORE(size) \
> +void __asan_report_store##size##_noabort(unsigned long addr) \
> +{ \
> + kasan_report(addr, size, true); \
> +} \
> +EXPORT_SYMBOL(__asan_report_store##size##_noabort)
> +
> +DEFINE_ASAN_REPORT_LOAD(1);
> +DEFINE_ASAN_REPORT_LOAD(2);
> +DEFINE_ASAN_REPORT_LOAD(4);
> +DEFINE_ASAN_REPORT_LOAD(8);
> +DEFINE_ASAN_REPORT_LOAD(16);
> +DEFINE_ASAN_REPORT_STORE(1);
> +DEFINE_ASAN_REPORT_STORE(2);
> +DEFINE_ASAN_REPORT_STORE(4);
> +DEFINE_ASAN_REPORT_STORE(8);
> +DEFINE_ASAN_REPORT_STORE(16);
> +
> +void __asan_report_load_n_noabort(unsigned long addr, size_t size)
> +{
> + kasan_report(addr, size, false);
> +}
> +EXPORT_SYMBOL(__asan_report_load_n_noabort);
> +
> +void __asan_report_store_n_noabort(unsigned long addr, size_t size)
> +{
> + kasan_report(addr, size, true);
> +}
> +EXPORT_SYMBOL(__asan_report_store_n_noabort);
> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> index 5117552..a5845a2 100644
> --- a/scripts/Makefile.lib
> +++ b/scripts/Makefile.lib
> @@ -119,6 +119,16 @@ _c_flags += $(if $(patsubst n%,, \
> $(CFLAGS_GCOV))
> endif
>
> +#
> +# Enable address sanitizer flags for kernel except some files or directories
> +# we don't want to check (depends on variables KASAN_SANITIZE_obj.o, KASAN_SANITIZE)
> +#
> +ifeq ($(CONFIG_KASAN),y)
> +_c_flags += $(if $(patsubst n%,, \
> + $(KASAN_SANITIZE_$(basetarget).o)$(KASAN_SANITIZE)$(CONFIG_KASAN)), \
> + $(CFLAGS_KASAN))
> +endif
> +
> # If building the kernel in a separate objtree expand all occurrences
> # of -Idir to -I$(srctree)/dir except for absolute paths (starting with '/').
>
> --
> 2.1.3
>
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