diff options
| author | Andrey Konovalov <andreyknvl@google.com> | 2015-11-05 18:51:01 -0800 |
|---|---|---|
| committer | Alex Shi <alex.shi@linaro.org> | 2016-04-11 15:58:30 +0800 |
| commit | b5e19433854e2650842c5a0c8a7cb12667af09f6 (patch) | |
| tree | 61fdeb2a5a487f65ac635b3e691c553acbf890e6 | |
| parent | deb5ced97e870de2d9bcd2806618c69ea0150140 (diff) | |
kasan: accurately determine the type of the bad access
Makes KASAN accurately determine the type of the bad access. If the shadow
byte value is in the [0, KASAN_SHADOW_SCALE_SIZE) range we can look at
the next shadow byte to determine the type of the access.
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Konstantin Serebryany <kcc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit cdf6a273dc4346277ab9d148ef29f6e058624a8c)
Signed-off-by: Alex Shi <alex.shi@linaro.org>
| -rw-r--r-- | mm/kasan/report.c | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/mm/kasan/report.c b/mm/kasan/report.c index 69d9315cb5c8..63e039f95813 100644 --- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -50,15 +50,26 @@ static const void *find_first_bad_addr(const void *addr, size_t size) static void print_error_description(struct kasan_access_info *info) { const char *bug_type = "unknown-crash"; - u8 shadow_val; + u8 *shadow_addr; 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); + shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr); - switch (shadow_val) { + /* + * If shadow byte value is in [0, KASAN_SHADOW_SCALE_SIZE) we can look + * at the next shadow byte to determine the type of the bad access. + */ + if (*shadow_addr > 0 && *shadow_addr <= KASAN_SHADOW_SCALE_SIZE - 1) + shadow_addr++; + + switch (*shadow_addr) { case 0 ... KASAN_SHADOW_SCALE_SIZE - 1: + /* + * In theory it's still possible to see these shadow values + * due to a data race in the kernel code. + */ bug_type = "out-of-bounds"; break; case KASAN_PAGE_REDZONE: |