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Commit 04415f0a authored by Andrey Konovalov's avatar Andrey Konovalov Committed by Trilok Soni
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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: default avatarAndrey 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Git-commit: cdf6a273dc4346277ab9d148ef29f6e058624a8c
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: default avatarTrilok Soni <tsoni@codeaurora.org>
parent dd9f6533

mm/kasan/report.c

+14 −3
Original line number Diff line number Diff line
@@ -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: