From: Dave Martin <Dave.Martin@arm.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: "H.J. Lu" <hjl.tools@gmail.com>,
"Chang S. Bae" <chang.seok.bae@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@suse.de>,
Andy Lutomirski <luto@kernel.org>,
the arch/x86 maintainers <x86@kernel.org>,
Len Brown <len.brown@intel.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Tony Luck <tony.luck@intel.com>,
"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
GNU C Library <libc-alpha@sourceware.org>,
linux-arch <linux-arch@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH 0/4] x86: Improve Minimum Alternate Stack Size
Date: Tue, 6 Oct 2020 18:00:21 +0100 [thread overview]
Message-ID: <20201006170020.GB6642@arm.com> (raw)
In-Reply-To: <7663eff0-6c94-f6bf-f3e2-93ede50e75ed@intel.com>
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
next prev parent reply other threads:[~2020-10-06 17:00 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-29 20:57 [RFC PATCH 0/4] x86: Improve Minimum Alternate Stack Size Chang S. Bae
2020-09-29 20:57 ` [RFC PATCH 1/4] x86/signal: Introduce helpers to get the maximum signal frame size Chang S. Bae
2020-10-05 13:42 ` Dave Martin
2020-10-06 17:45 ` Bae, Chang Seok
2020-10-07 10:05 ` Dave Martin
2020-10-08 22:43 ` Bae, Chang Seok
2020-10-12 13:26 ` Dave Martin
2020-09-29 20:57 ` [RFC PATCH 2/4] x86/elf: Support a new ELF aux vector AT_MINSIGSTKSZ Chang S. Bae
2020-09-29 20:57 ` [RFC PATCH 3/4] x86/signal: Prevent an alternate stack overflow before a signal delivery Chang S. Bae
2020-09-29 20:57 ` [RFC PATCH 4/4] selftest/x86/signal: Include test cases for validating sigaltstack Chang S. Bae
2020-10-05 13:45 ` [RFC PATCH 0/4] x86: Improve Minimum Alternate Stack Size Dave Martin
2020-10-05 21:17 ` H.J. Lu
2020-10-06 9:25 ` Dave Martin
2020-10-06 12:12 ` H.J. Lu
2020-10-06 15:18 ` H.J. Lu
2020-10-06 15:43 ` Dave Martin
2020-10-06 16:52 ` H.J. Lu
2020-10-06 15:25 ` Dave Martin
2020-10-06 15:33 ` Dave Hansen
2020-10-06 17:00 ` Dave Martin [this message]
2020-10-06 18:21 ` Florian Weimer
2020-10-07 10:19 ` Dave Martin
2020-10-06 18:30 ` Dave Hansen
2020-10-07 10:20 ` Dave Martin
2020-10-06 15:34 ` H.J. Lu
2020-10-06 16:55 ` Dave Martin
2020-10-06 17:44 ` H.J. Lu
2020-10-07 10:47 ` Dave Martin
2020-10-07 13:30 ` H.J. Lu
2020-10-07 15:45 ` Dave Martin
2020-10-07 17:43 ` H.J. Lu
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