Commit 88fc7eb5 authored by Thomas Weißschuh's avatar Thomas Weißschuh Committed by Paul E. McKenney
Browse files

tools/nolibc: ensure stack protector guard is never zero 



The all-zero pattern is one of the more probable out-of-bound writes so
add a special case to not accidentally accept it.

Also it enables the reliable detection of stack protector initialization
during testing.

Signed-off-by: default avatarThomas Weißschuh <linux@weissschuh.net>
Signed-off-by: default avatarWilly Tarreau <w@1wt.eu>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 7a9b2345

tools/include/nolibc/stackprotector.h

+3 −2
Original line number Original line Diff line number Diff line
@@ -45,7 +45,8 @@ __attribute__((weak,no_stack_protector,section(".text.nolibc_stack_chk"))) 
void __stack_chk_init(void)

void __stack_chk_init(void)

{

{

	my_syscall3(__NR_getrandom, &__stack_chk_guard, sizeof(__stack_chk_guard), 0);

	my_syscall3(__NR_getrandom, &__stack_chk_guard, sizeof(__stack_chk_guard), 0);

	/* a bit more randomness in case getrandom() fails */

	/* a bit more randomness in case getrandom() fails, ensure the guard is never 0 */

	if (__stack_chk_guard != (uintptr_t) &__stack_chk_guard)

		__stack_chk_guard ^= (uintptr_t) &__stack_chk_guard;

		__stack_chk_guard ^= (uintptr_t) &__stack_chk_guard;

}

}

#endif /* defined(NOLIBC_STACKPROTECTOR) */

#endif /* defined(NOLIBC_STACKPROTECTOR) */