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authorArjan van de Ven <arjan@linux.intel.com>2008-07-12 09:36:38 -0700
committerIngo Molnar <mingo@elte.hu>2008-07-13 21:08:38 +0200
commitaf9ff7868f0f76d3364351b1641b9dfa99588e77 (patch)
tree4fbbf7a306a9a3ebbfbbe678396f0594bd18cb68 /kernel/panic.c
parentaa92db14270b79f0f91a9060b547a46f9e2639da (diff)
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x86: simplify stackprotector self-check
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>
Diffstat (limited to 'kernel/panic.c')
-rw-r--r--kernel/panic.c29
1 files changed, 7 insertions, 22 deletions
diff --git a/kernel/panic.c b/kernel/panic.c
index 28153aec710..87445a894c3 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -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;
}
/*