diff options
| author | Arjan van de Ven <arjan@linux.intel.com> | 2008-07-12 09:36:38 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-07-13 21:08:38 +0200 |
| commit | af9ff7868f0f76d3364351b1641b9dfa99588e77 (patch) | |
| tree | 4fbbf7a306a9a3ebbfbbe678396f0594bd18cb68 | |
| parent | aa92db14270b79f0f91a9060b547a46f9e2639da (diff) | |
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>
| -rw-r--r-- | include/asm-x86/pda.h | 1 | ||||
| -rw-r--r-- | kernel/panic.c | 29 |
2 files changed, 8 insertions, 22 deletions
diff --git a/include/asm-x86/pda.h b/include/asm-x86/pda.h index 62b734986a4..a5ff5bb7629 100644 --- a/include/asm-x86/pda.h +++ b/include/asm-x86/pda.h @@ -131,4 +131,5 @@ do { \ #define PDA_STACKOFFSET (5*8) +#define refresh_stack_canary() write_pda(stack_canary, current->stack_canary) #endif 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; } /* |