Messages in this thread | | | Date | Tue, 6 Oct 2020 18:00:21 +0100 | From | Dave Martin <> | Subject | Re: [RFC PATCH 0/4] x86: Improve Minimum Alternate Stack Size |
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On Tue, Oct 06, 2020 at 08:33:47AM -0700, Dave Hansen wrote: > On 10/6/20 8:25 AM, Dave Martin wrote: > > Or are people reporting real stack overruns on x86 today? > > We have real overruns. We have ~2800 bytes of XSAVE (regisiter) state > mostly from AVX-512, and a 2048 byte MINSIGSTKSZ.
Right. Out of interest, do you believe that's a direct consequence of the larger kernel-generated signal frame, or does the expansion of userspace stack frames play a role too?
In practice software just assumes SIGSTKSZ and then ignores the problem until / unless an actual stack overflow is seen.
There's probably a lot of software out there whose stack is theoretically too small even without AVX-512 etc. in the mix, especially when considering the possibility of nested signals...
Cheers ---Dave
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