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author | Ingo Molnar <mingo@elte.hu> | 2008-07-13 21:42:44 +0200 |
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committer | Ingo Molnar <mingo@elte.hu> | 2008-07-13 21:50:46 +0200 |
commit | 4f962d4d65923d7b722192e729840cfb79af0a5a (patch) | |
tree | 33576a5a4093f2f937dd40be899d92982f6232bd /kernel/panic.c | |
parent | af9ff7868f0f76d3364351b1641b9dfa99588e77 (diff) | |
download | kernel_goldelico_gta04-4f962d4d65923d7b722192e729840cfb79af0a5a.zip kernel_goldelico_gta04-4f962d4d65923d7b722192e729840cfb79af0a5a.tar.gz kernel_goldelico_gta04-4f962d4d65923d7b722192e729840cfb79af0a5a.tar.bz2 |
stackprotector: remove self-test
turns out gcc generates such stackprotector-failure sequences
in certain circumstances:
movq -8(%rbp), %rax # D.16032,
xorq %gs:40, %rax #,
jne .L17 #,
leave
ret
.L17:
call __stack_chk_fail #
.size __stack_chk_test_func, .-__stack_chk_test_func
.section .init.text,"ax",@progbits
.type panic_setup, @function
panic_setup:
pushq %rbp #
note that there's no jump back to the failing context after the
call to __stack_chk_fail - i.e. it has a ((noreturn)) attribute.
Which is fair enough in the normal case but kills the self-test.
(as we cannot reliably return in the self-test)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/panic.c')
-rw-r--r-- | kernel/panic.c | 47 |
1 files changed, 0 insertions, 47 deletions
diff --git a/kernel/panic.c b/kernel/panic.c index 87445a8..c35c9ec 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -329,62 +329,15 @@ EXPORT_SYMBOL(warn_on_slowpath); #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. - */ -static noinline void __stack_chk_test_func(void) -{ - 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) -{ - printk(KERN_INFO "Testing -fstack-protector-all feature\n"); - __stack_check_testing = (unsigned long)&__stack_chk_test_func; - __stack_chk_test_func(); - if (__stack_check_testing) { - printk(KERN_ERR "-fstack-protector-all test failed\n"); - WARN_ON(1); - }; - current->stack_canary = ~current->stack_canary; - refresh_stack_canary(); - return 0; -} /* * Called when gcc's -fstack-protector feature is used, and * gcc detects corruption of the on-stack canary value */ void __stack_chk_fail(void) { - if (__stack_check_testing == (unsigned long)&__stack_chk_test_func) { - long delta; - - delta = (unsigned long)__builtin_return_address(0) - - __stack_check_testing; - /* - * The test needs to happen inside the test function, so - * check if the return address is close to that function. - * The function is only 2 dozen bytes long, but keep a wide - * safety margin to avoid panic()s for normal users regardless - * of the quality of the compiler. - */ - if (delta >= 0 && delta <= 400) { - __stack_check_testing = 0; - return; - } - } panic("stack-protector: Kernel stack is corrupted in: %p\n", __builtin_return_address(0)); } EXPORT_SYMBOL(__stack_chk_fail); -late_initcall(__stack_chk_test); #endif |