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From:   "Bae, Chang Seok" <chang.seok.bae@intel.com>
To:     Borislav Petkov <bp@alien8.de>
CC:     Andy Lutomirski <luto@kernel.org>,
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Subject: Re: [PATCH v7 5/6] x86/signal: Detect and prevent an alternate signal
 stack overflow
Thread-Topic: [PATCH v7 5/6] x86/signal: Detect and prevent an alternate
 signal stack overflow
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Date:   Mon, 12 Apr 2021 22:30:23 +0000
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On Mar 26, 2021, at 03:30, Borislav Petkov <bp@alien8.de> wrote:
> On Thu, Mar 25, 2021 at 09:56:53PM -0700, Andy Lutomirski wrote:
>> We really ought to have a SIGSIGFAIL signal that's sent, double-fault
>> style, when we fail to send a signal.
>=20
> Yeap, we should be able to tell userspace that we couldn't send a
> signal, hohumm.

Hi Boris,

Let me clarify some details as preparing to include this in a revision.

So, IIUC, a number needs to be assigned for this new SIGFAIL. At a glance, =
not
sure which one to pick there in signal.h -- 1-31 fully occupied and the res=
t
for 33 different real-time signals.

Also, perhaps, force_sig(SIGFAIL) here, instead of return -1 -- to die with
SIGSEGV.

Thanks,
Chang