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authorAndrey Ryabinin <aryabinin@virtuozzo.com>2019-03-06 02:41:20 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2019-03-06 08:07:13 +0300
commit7771bdbbfd3d6f204631b6fd9e1bbc30cd15918e (patch)
tree1f715a5317669f6473d1d4ddb4f5bf761e918e71 /mm/kasan
parent46612b751c4941c5c0472ddf04027e877ae5990f (diff)
downloadlinux-7771bdbbfd3d6f204631b6fd9e1bbc30cd15918e.tar.xz
kasan: remove use after scope bugs detection.
Use after scope bugs detector seems to be almost entirely useless for the linux kernel. It exists over two years, but I've seen only one valid bug so far [1]. And the bug was fixed before it has been reported. There were some other use-after-scope reports, but they were false-positives due to different reasons like incompatibility with structleak plugin. This feature significantly increases stack usage, especially with GCC < 9 version, and causes a 32K stack overflow. It probably adds performance penalty too. Given all that, let's remove use-after-scope detector entirely. While preparing this patch I've noticed that we mistakenly enable use-after-scope detection for clang compiler regardless of CONFIG_KASAN_EXTRA setting. This is also fixed now. [1] http://lkml.kernel.org/r/<20171129052106.rhgbjhhis53hkgfn@wfg-t540p.sh.intel.com> Link: http://lkml.kernel.org/r/20190111185842.13978-1-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by: Will Deacon <will.deacon@arm.com> [arm64] Cc: Qian Cai <cai@lca.pw> Cc: Alexander Potapenko <glider@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/kasan')
-rw-r--r--mm/kasan/generic.c19
-rw-r--r--mm/kasan/generic_report.c3
-rw-r--r--mm/kasan/kasan.h3
3 files changed, 0 insertions, 25 deletions
diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
index ccb6207276e3..504c79363a34 100644
--- a/mm/kasan/generic.c
+++ b/mm/kasan/generic.c
@@ -275,25 +275,6 @@ EXPORT_SYMBOL(__asan_storeN_noabort);
void __asan_handle_no_return(void) {}
EXPORT_SYMBOL(__asan_handle_no_return);
-/* Emitted by compiler to poison large objects when they go out of scope. */
-void __asan_poison_stack_memory(const void *addr, size_t size)
-{
- /*
- * Addr is KASAN_SHADOW_SCALE_SIZE-aligned and the object is surrounded
- * by redzones, so we simply round up size to simplify logic.
- */
- kasan_poison_shadow(addr, round_up(size, KASAN_SHADOW_SCALE_SIZE),
- KASAN_USE_AFTER_SCOPE);
-}
-EXPORT_SYMBOL(__asan_poison_stack_memory);
-
-/* Emitted by compiler to unpoison large objects when they go into scope. */
-void __asan_unpoison_stack_memory(const void *addr, size_t size)
-{
- kasan_unpoison_shadow(addr, size);
-}
-EXPORT_SYMBOL(__asan_unpoison_stack_memory);
-
/* Emitted by compiler to poison alloca()ed objects. */
void __asan_alloca_poison(unsigned long addr, size_t size)
{
diff --git a/mm/kasan/generic_report.c b/mm/kasan/generic_report.c
index 5e12035888f2..36c645939bc9 100644
--- a/mm/kasan/generic_report.c
+++ b/mm/kasan/generic_report.c
@@ -82,9 +82,6 @@ static const char *get_shadow_bug_type(struct kasan_access_info *info)
case KASAN_KMALLOC_FREE:
bug_type = "use-after-free";
break;
- case KASAN_USE_AFTER_SCOPE:
- bug_type = "use-after-scope";
- break;
case KASAN_ALLOCA_LEFT:
case KASAN_ALLOCA_RIGHT:
bug_type = "alloca-out-of-bounds";
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index ea51b2d898ec..3e0c11f7d7a1 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -34,7 +34,6 @@
#define KASAN_STACK_MID 0xF2
#define KASAN_STACK_RIGHT 0xF3
#define KASAN_STACK_PARTIAL 0xF4
-#define KASAN_USE_AFTER_SCOPE 0xF8
/*
* alloca redzone shadow values
@@ -187,8 +186,6 @@ void __asan_unregister_globals(struct kasan_global *globals, size_t size);
void __asan_loadN(unsigned long addr, size_t size);
void __asan_storeN(unsigned long addr, size_t size);
void __asan_handle_no_return(void);
-void __asan_poison_stack_memory(const void *addr, size_t size);
-void __asan_unpoison_stack_memory(const void *addr, size_t size);
void __asan_alloca_poison(unsigned long addr, size_t size);
void __asan_allocas_unpoison(const void *stack_top, const void *stack_bottom);