Messages in this thread Patch in this message | | | From | riel@redhat ... | Subject | [PATCH 3/5] x86: ascii armor the x86_64 boot init stack canary | Date | Wed, 24 May 2017 11:57:49 -0400 |
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From: Rik van Riel <riel@redhat.com>
Use the ascii-armor canary to prevent unterminated C string overflows from being able to successfully overwrite the canary, even if they somehow obtain the canary value.
Inspired by execshield ascii-armor and Daniel Micay's linux-hardened tree.
Signed-off-by: Rik van Riel <riel@redhat.com> --- arch/x86/include/asm/stackprotector.h | 1 + 1 file changed, 1 insertion(+)
diff --git a/arch/x86/include/asm/stackprotector.h b/arch/x86/include/asm/stackprotector.h index dcbd9bcce714..8abedf1d650e 100644 --- a/arch/x86/include/asm/stackprotector.h +++ b/arch/x86/include/asm/stackprotector.h @@ -74,6 +74,7 @@ static __always_inline void boot_init_stack_canary(void) get_random_bytes(&canary, sizeof(canary)); tsc = rdtsc(); canary += tsc + (tsc << 32UL); + canary &= CANARY_MASK; current->stack_canary = canary; #ifdef CONFIG_X86_64 -- 2.9.3
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