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x86: simplify stackprotector self-check

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Clean up the code by removing no longer needed code;
make sure the pda is updated and kept in sync

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Arjan van de Ven 2008-07-12 09:36:38 -07:00 committed by Ingo Molnar
parent aa92db1427
commit af9ff7868f
2 changed files with 8 additions and 22 deletions
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1
include/asm-x86/pda.h
View file

@ -131,4 +131,5 @@ do { \
#define PDA_STACKOFFSET (5*8)
#define refresh_stack_canary() write_pda(stack_canary, current->stack_canary)
#endif

29
kernel/panic.c
View file

@ -328,37 +328,21 @@ EXPORT_SYMBOL(warn_on_slowpath);
#ifndef GCC_HAS_SP
#warning You have selected the CONFIG_CC_STACKPROTECTOR option, but the gcc used does not support this.
#endif
static unsigned long __stack_check_testing;
/*
* Self test function for the stack-protector feature.
* This test requires that the local variable absolutely has
* a stack slot, hence the barrier()s.
* a stack slot.
*/
static noinline void __stack_chk_test_func(void)
{
unsigned long foo;
barrier();
/*
* we need to make sure we're not about to clobber the return address,
* while real exploits do this, it's unhealthy on a running system.
* Besides, if we would, the test is already failed anyway so
* time to pull the emergency brake on it.
*/
if ((unsigned long)__builtin_return_address(0) ==
*(((unsigned long *)&foo)+1)) {
printk(KERN_ERR "No -fstack-protector-stack-frame!\n");
}
#ifdef CONFIG_FRAME_POINTER
/* We also don't want to clobber the frame pointer */
if ((unsigned long)__builtin_return_address(0) ==
*(((unsigned long *)&foo)+2)) {
printk(KERN_ERR "No -fstack-protector-stack-frame!\n");
}
#endif
if (current->stack_canary != *(((unsigned long *)&foo)+1))
printk(KERN_ERR "No -fstack-protector canary found\n");
unsigned long dummy_buffer[64]; /* force gcc to use the canary */
current->stack_canary = ~current->stack_canary;
refresh_stack_canary();
dummy_buffer[3] = 1; /* fool gcc into keeping the variable */
}
static int __stack_chk_test(void)
@ -371,6 +355,7 @@ static int __stack_chk_test(void)
WARN_ON(1);
};
current->stack_canary = ~current->stack_canary;
refresh_stack_canary();
return 0;
}
/*