diff options
| author | Tejun Heo <tj@kernel.org> | 2009-02-09 16:17:40 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-02-10 02:42:01 +0300 |
| commit | 60a5317ff0f42dd313094b88f809f63041568b08 (patch) | |
| tree | 307dfd9715fbc9ff83c3c3ae3b0e8f03888083f2 /arch/x86/include/asm/segment.h | |
| parent | ccbeed3a05908d201b47b6c3dd1a373138bba566 (diff) | |
| download | linux-60a5317ff0f42dd313094b88f809f63041568b08.tar.xz | |
x86: implement x86_32 stack protector
Impact: stack protector for x86_32
Implement stack protector for x86_32. GDT entry 28 is used for it.
It's set to point to stack_canary-20 and have the length of 24 bytes.
CONFIG_CC_STACKPROTECTOR turns off CONFIG_X86_32_LAZY_GS and sets %gs
to the stack canary segment on entry. As %gs is otherwise unused by
the kernel, the canary can be anywhere. It's defined as a percpu
variable.
x86_32 exception handlers take register frame on stack directly as
struct pt_regs. With -fstack-protector turned on, gcc copies the
whole structure after the stack canary and (of course) doesn't copy
back on return thus losing all changed. For now, -fno-stack-protector
is added to all files which contain those functions. We definitely
need something better.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/include/asm/segment.h')
| -rw-r--r-- | arch/x86/include/asm/segment.h | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h index 1dc1b51ac623..14e0ed86a6f9 100644 --- a/arch/x86/include/asm/segment.h +++ b/arch/x86/include/asm/segment.h @@ -61,7 +61,7 @@ * * 26 - ESPFIX small SS * 27 - per-cpu [ offset to per-cpu data area ] - * 28 - unused + * 28 - stack_canary-20 [ for stack protector ] * 29 - unused * 30 - unused * 31 - TSS for double fault handler @@ -95,6 +95,13 @@ #define __KERNEL_PERCPU 0 #endif +#define GDT_ENTRY_STACK_CANARY (GDT_ENTRY_KERNEL_BASE + 16) +#ifdef CONFIG_CC_STACKPROTECTOR +#define __KERNEL_STACK_CANARY (GDT_ENTRY_STACK_CANARY * 8) +#else +#define __KERNEL_STACK_CANARY 0 +#endif + #define GDT_ENTRY_DOUBLEFAULT_TSS 31 /* |