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stackprotector: better self-test

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check stackprotector functionality by manipulating the canary briefly
during bootup.

far more robust than trying to overflow the stack. (which is architecture
dependent, etc.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Arjan van de Ven 2008-07-11 05:09:55 -07:00 committed by Ingo Molnar
parent 5ce001b0e5
commit aa92db1427
1 changed files with 5 additions and 8 deletions
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13
kernel/panic.c
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@ -347,22 +347,18 @@ static noinline void __stack_chk_test_func(void)
if ((unsigned long)__builtin_return_address(0) == if ((unsigned long)__builtin_return_address(0) ==
*(((unsigned long *)&foo)+1)) { *(((unsigned long *)&foo)+1)) {
printk(KERN_ERR "No -fstack-protector-stack-frame!\n"); printk(KERN_ERR "No -fstack-protector-stack-frame!\n");
return;
} }
#ifdef CONFIG_FRAME_POINTER #ifdef CONFIG_FRAME_POINTER
/* We also don't want to clobber the frame pointer */ /* We also don't want to clobber the frame pointer */
if ((unsigned long)__builtin_return_address(0) == if ((unsigned long)__builtin_return_address(0) ==
*(((unsigned long *)&foo)+2)) { *(((unsigned long *)&foo)+2)) {
printk(KERN_ERR "No -fstack-protector-stack-frame!\n"); printk(KERN_ERR "No -fstack-protector-stack-frame!\n");
return;
} }
#endif #endif
barrier(); if (current->stack_canary != *(((unsigned long *)&foo)+1))
if (current->stack_canary == *(((unsigned long *)&foo)+1))
*(((unsigned long *)&foo)+1) = 0;
else
printk(KERN_ERR "No -fstack-protector canary found\n"); printk(KERN_ERR "No -fstack-protector canary found\n");
barrier();
current->stack_canary = ~current->stack_canary;
} }
static int __stack_chk_test(void) static int __stack_chk_test(void)
@ -373,7 +369,8 @@ static int __stack_chk_test(void)
if (__stack_check_testing) { if (__stack_check_testing) {
printk(KERN_ERR "-fstack-protector-all test failed\n"); printk(KERN_ERR "-fstack-protector-all test failed\n");
WARN_ON(1); WARN_ON(1);
} };
current->stack_canary = ~current->stack_canary;
return 0; return 0;
} }
/* /*