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    SubjectRe: [PATCH 11/11] x86: implement x86_32 stack protector
    Brian Gerst wrote:
    > On Mon, Feb 9, 2009 at 8:39 AM, Tejun Heo <> 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 <>
    > 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?

    Yeah, it seems I forgot to subtract 20 from the address. Will prep a
    patch. Thanks for spotting it.


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      Last update: 2009-02-10 16:43    [W:0.020 / U:474.604 seconds]
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