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From: Thomas Gleixner <tglx@linutronix.de>
To: lkp@lists.01.org
Subject: Re: [x86/uaccess] 9c5743dff4: WARNING:at_arch/x86/mm/extable.c:#ex_handler_fprestore
Date: Sun, 15 May 2022 16:54:47 +0200	[thread overview]
Message-ID: <87pmkerglk.ffs@tglx> (raw)
In-Reply-To: <8735hbryn6.ffs@tglx>

[-- Attachment #1: Type: text/plain, Size: 753 bytes --]

On Sun, May 15 2022 at 10:25, Thomas Gleixner wrote:
> On Fri, May 13 2022 at 09:52, Linus Torvalds wrote:
> The code which copies the ptrace supplied state has a pile of sanity
> checks to catch invalid state, but I wouldn't bet my hat on it that it's
> 100% complete. We can be more defensive here, but I would be surprised.
>
> Something like the untested below. I'll expose it to some testing to see
> what explodes.

I was not able to get something broken past the existing sanity checks
which was caught by the trial restore. I seems the FPU units are pretty
resilent against random nonsense except for the XSTATE header and the
MXCRS content. Though I ponder to just add that trial restore due to
paranoia.

Thanks,

        tglx

WARNING: multiple messages have this Message-ID (diff)
From: Thomas Gleixner <tglx@linutronix.de>
To: Linus Torvalds <torvalds@linux-foundation.org>,
	kernel test robot <oliver.sang@intel.com>,
	Eric Biggers <ebiggers@google.com>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Naresh Kamboju <naresh.kamboju@linaro.org>,
	LKML <linux-kernel@vger.kernel.org>,
	lkp@lists.01.org, kernel test robot <lkp@intel.com>,
	the arch/x86 maintainers <x86@kernel.org>
Subject: Re: [x86/uaccess] 9c5743dff4: WARNING:at_arch/x86/mm/extable.c:#ex_handler_fprestore
Date: Sun, 15 May 2022 16:54:47 +0200	[thread overview]
Message-ID: <87pmkerglk.ffs@tglx> (raw)
In-Reply-To: <8735hbryn6.ffs@tglx>

On Sun, May 15 2022 at 10:25, Thomas Gleixner wrote:
> On Fri, May 13 2022 at 09:52, Linus Torvalds wrote:
> The code which copies the ptrace supplied state has a pile of sanity
> checks to catch invalid state, but I wouldn't bet my hat on it that it's
> 100% complete. We can be more defensive here, but I would be surprised.
>
> Something like the untested below. I'll expose it to some testing to see
> what explodes.

I was not able to get something broken past the existing sanity checks
which was caught by the trial restore. I seems the FPU units are pretty
resilent against random nonsense except for the XSTATE header and the
MXCRS content. Though I ponder to just add that trial restore due to
paranoia.

Thanks,

        tglx

  reply	other threads:[~2022-05-15 14:54 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-13  8:54 [x86/uaccess] 9c5743dff4: WARNING:at_arch/x86/mm/extable.c:#ex_handler_fprestore kernel test robot
2022-05-13  8:54 ` kernel test robot
2022-05-13 16:52 ` Linus Torvalds
2022-05-13 16:52   ` Linus Torvalds
2022-05-13 17:12   ` Borislav Petkov
2022-05-13 17:12     ` Borislav Petkov
2022-05-15  3:06     ` Oliver Sang
2022-05-15  3:06       ` Oliver Sang
2022-05-15  8:25   ` Thomas Gleixner
2022-05-15  8:25     ` Thomas Gleixner
2022-05-15 14:54     ` Thomas Gleixner [this message]
2022-05-15 14:54       ` Thomas Gleixner

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