Messages in this thread | | | Date | Tue, 10 Feb 2009 10:25:06 -0500 | Subject | Re: [PATCH 11/11] x86: implement x86_32 stack protector | From | Brian Gerst <> |
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On Mon, Feb 9, 2009 at 8:39 AM, Tejun Heo <tj@kernel.org> wrote: > 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>
Am I missing something, or does this patch not actually implement the offset of the start of the segment by 20 from the stack_canary variable?
-- Brian Gerst
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