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Re: [tip:x86/urgent] x86/fpu/xstate: Fix xcomp_bv in XSAVES header

Started byYu-cheng Yu <yu-cheng.yu@intel.com>
First post2017-02-14 22:40 +0100
Last post2017-02-16 19:00 +0100
Articles 4 — 2 participants

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  Re: [tip:x86/urgent] x86/fpu/xstate: Fix xcomp_bv in XSAVES header Yu-cheng Yu <yu-cheng.yu@intel.com> - 2017-02-14 22:40 +0100
    Re: [tip:x86/urgent] x86/fpu/xstate: Fix xcomp_bv in XSAVES header Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-15 00:00 +0100
    Re: [tip:x86/urgent] x86/fpu/xstate: Fix xcomp_bv in XSAVES header Yu-cheng Yu <yu-cheng.yu@intel.com> - 2017-02-16 19:00 +0100
    Re: [tip:x86/urgent] x86/fpu/xstate: Fix xcomp_bv in XSAVES header Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-16 19:00 +0100

#1580886 — Re: [tip:x86/urgent] x86/fpu/xstate: Fix xcomp_bv in XSAVES header

FromYu-cheng Yu <yu-cheng.yu@intel.com>
Date2017-02-14 22:40 +0100
SubjectRe: [tip:x86/urgent] x86/fpu/xstate: Fix xcomp_bv in XSAVES header
Message-ID<taSZl-75C-29@gated-at.bofh.it>
On Tue, Jan 24, 2017 at 12:46:17AM -0800, tip-bot for Yu-cheng Yu wrote:
> Commit-ID:  dffba9a31c7769be3231c420d4b364c92ba3f1ac
> Gitweb:     http://git.kernel.org/tip/dffba9a31c7769be3231c420d4b364c92ba3f1ac
> Author:     Yu-cheng Yu <yu-cheng.yu@intel.com>
> AuthorDate: Mon, 23 Jan 2017 14:54:44 -0800
> Committer:  Ingo Molnar <mingo@kernel.org>
> CommitDate: Tue, 24 Jan 2017 09:04:48 +0100
> 
> x86/fpu/xstate: Fix xcomp_bv in XSAVES header
> 
> The compacted-format XSAVES area is determined at boot time and
> never changed after.  The field xsave.header.xcomp_bv indicates
> which components are in the fixed XSAVES format.
> 
> In fpstate_init() we did not set xcomp_bv to reflect the XSAVES
> format since at the time there is no valid data.
> 
> However, after we do copy_init_fpstate_to_fpregs() in fpu__clear(),
> as in commit:
> 
>   b22cbe404a9c x86/fpu: Fix invalid FPU ptrace state after execve()
> 
> and when __fpu_restore_sig() does fpu__restore() for a COMPAT-mode
> app, a #GP occurs.  This can be easily triggered by doing valgrind on
> a COMPAT-mode "Hello World," as reported by Joakim Tjernlund and
> others:
> 
> 	https://bugzilla.kernel.org/show_bug.cgi?id=190061
> 
> Fix it by setting xcomp_bv correctly.
> 

Please consider pulling this into the stable tree because my previous
patch in commit: 

  b22cbe404a9c x86/fpu: Fix invalid FPU ptrace state after execve()

exposes the same issue in the stable tree.

Thanks,
Yu-cheng

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#1580935

FromGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Date2017-02-15 00:00 +0100
Message-ID<taUeK-7RX-5@gated-at.bofh.it>
In reply to#1580886
On Tue, Feb 14, 2017 at 01:26:41PM -0800, Yu-cheng Yu wrote:
> On Tue, Jan 24, 2017 at 12:46:17AM -0800, tip-bot for Yu-cheng Yu wrote:
> > Commit-ID:  dffba9a31c7769be3231c420d4b364c92ba3f1ac
> > Gitweb:     http://git.kernel.org/tip/dffba9a31c7769be3231c420d4b364c92ba3f1ac
> > Author:     Yu-cheng Yu <yu-cheng.yu@intel.com>
> > AuthorDate: Mon, 23 Jan 2017 14:54:44 -0800
> > Committer:  Ingo Molnar <mingo@kernel.org>
> > CommitDate: Tue, 24 Jan 2017 09:04:48 +0100
> > 
> > x86/fpu/xstate: Fix xcomp_bv in XSAVES header
> > 
> > The compacted-format XSAVES area is determined at boot time and
> > never changed after.  The field xsave.header.xcomp_bv indicates
> > which components are in the fixed XSAVES format.
> > 
> > In fpstate_init() we did not set xcomp_bv to reflect the XSAVES
> > format since at the time there is no valid data.
> > 
> > However, after we do copy_init_fpstate_to_fpregs() in fpu__clear(),
> > as in commit:
> > 
> >   b22cbe404a9c x86/fpu: Fix invalid FPU ptrace state after execve()
> > 
> > and when __fpu_restore_sig() does fpu__restore() for a COMPAT-mode
> > app, a #GP occurs.  This can be easily triggered by doing valgrind on
> > a COMPAT-mode "Hello World," as reported by Joakim Tjernlund and
> > others:
> > 
> > 	https://bugzilla.kernel.org/show_bug.cgi?id=190061
> > 
> > Fix it by setting xcomp_bv correctly.
> > 
> 
> Please consider pulling this into the stable tree because my previous
> patch in commit: 
> 
>   b22cbe404a9c x86/fpu: Fix invalid FPU ptrace state after execve()
> 
> exposes the same issue in the stable tree.

Ah, thanks, I'll do that for the next round of stable releases after the
ones that happen tomorrow.

greg k-h

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#1582748

FromYu-cheng Yu <yu-cheng.yu@intel.com>
Date2017-02-16 19:00 +0100
Message-ID<tbyvx-1iO-35@gated-at.bofh.it>
In reply to#1580886
On Thu, Feb 16, 2017 at 09:51:12AM -0800, Greg Kroah-Hartman wrote:
> On Tue, Feb 14, 2017 at 01:26:41PM -0800, Yu-cheng Yu wrote:
> > On Tue, Jan 24, 2017 at 12:46:17AM -0800, tip-bot for Yu-cheng Yu wrote:
> > > Commit-ID:  dffba9a31c7769be3231c420d4b364c92ba3f1ac
> > > Gitweb:     http://git.kernel.org/tip/dffba9a31c7769be3231c420d4b364c92ba3f1ac
> > > Author:     Yu-cheng Yu <yu-cheng.yu@intel.com>
> > > AuthorDate: Mon, 23 Jan 2017 14:54:44 -0800
> > > Committer:  Ingo Molnar <mingo@kernel.org>
> > > CommitDate: Tue, 24 Jan 2017 09:04:48 +0100
> > > 
> > > x86/fpu/xstate: Fix xcomp_bv in XSAVES header

> I just tried to apply this, and it does not apply at all.  Can you
> please provide a backported version that you have verified will work, so
> that I can apply it?

I will do that.

Thanks,
Yu-cheng

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#1582759

FromGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Date2017-02-16 19:00 +0100
Message-ID<tbyvx-1iO-37@gated-at.bofh.it>
In reply to#1580886
On Tue, Feb 14, 2017 at 01:26:41PM -0800, Yu-cheng Yu wrote:
> On Tue, Jan 24, 2017 at 12:46:17AM -0800, tip-bot for Yu-cheng Yu wrote:
> > Commit-ID:  dffba9a31c7769be3231c420d4b364c92ba3f1ac
> > Gitweb:     http://git.kernel.org/tip/dffba9a31c7769be3231c420d4b364c92ba3f1ac
> > Author:     Yu-cheng Yu <yu-cheng.yu@intel.com>
> > AuthorDate: Mon, 23 Jan 2017 14:54:44 -0800
> > Committer:  Ingo Molnar <mingo@kernel.org>
> > CommitDate: Tue, 24 Jan 2017 09:04:48 +0100
> > 
> > x86/fpu/xstate: Fix xcomp_bv in XSAVES header
> > 
> > The compacted-format XSAVES area is determined at boot time and
> > never changed after.  The field xsave.header.xcomp_bv indicates
> > which components are in the fixed XSAVES format.
> > 
> > In fpstate_init() we did not set xcomp_bv to reflect the XSAVES
> > format since at the time there is no valid data.
> > 
> > However, after we do copy_init_fpstate_to_fpregs() in fpu__clear(),
> > as in commit:
> > 
> >   b22cbe404a9c x86/fpu: Fix invalid FPU ptrace state after execve()
> > 
> > and when __fpu_restore_sig() does fpu__restore() for a COMPAT-mode
> > app, a #GP occurs.  This can be easily triggered by doing valgrind on
> > a COMPAT-mode "Hello World," as reported by Joakim Tjernlund and
> > others:
> > 
> > 	https://bugzilla.kernel.org/show_bug.cgi?id=190061
> > 
> > Fix it by setting xcomp_bv correctly.
> > 
> 
> Please consider pulling this into the stable tree because my previous
> patch in commit: 
> 
>   b22cbe404a9c x86/fpu: Fix invalid FPU ptrace state after execve()
> 
> exposes the same issue in the stable tree.

I just tried to apply this, and it does not apply at all.  Can you
please provide a backported version that you have verified will work, so
that I can apply it?

thanks,

greg k-h

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