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arm64: ascii armor the arm64 boot init stack canary

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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.

Link: http://lkml.kernel.org/r/20170524155751.424-5-riel@redhat.com
Signed-off-by: Rik van Riel <riel@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Daniel Micay <danielmicay@gmail.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Rik van Riel 2017-07-12 14:36:26 -07:00 committed by Linus Torvalds
parent bf9eb54438
commit d21f54988b
1 changed files with 1 additions and 0 deletions
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1
arch/arm64/include/asm/stackprotector.h
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@ -30,6 +30,7 @@ static __always_inline void boot_init_stack_canary(void)
/* Try to get a semi random initial value. */
get_random_bytes(&canary, sizeof(canary));
canary ^= LINUX_VERSION_CODE;
canary &= CANARY_MASK;
current->stack_canary = canary;
__stack_chk_guard = current->stack_canary;