This is a note to let you know that I've just added the patch titled
x86/fpu/xstate: Fix xcomp_bv in XSAVES header
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-fpu-xstate-fix-xcomp_bv-in-xsaves-header.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From dffba9a31c7769be3231c420d4b364c92ba3f1ac Mon Sep 17 00:00:00 2001
From: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
Date: Mon, 23 Jan 2017 14:54:44 -0800
Subject: x86/fpu/xstate: Fix xcomp_bv in XSAVES header
From: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
commit dffba9a31c7769be3231c420d4b364c92ba3f1ac upstream.
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.
This patch also moves the xcomp_bv initialization to the proper
place, which was in copyin_to_xsaves() as of:
4c833368f0bf x86/fpu: Set the xcomp_bv when we fake up a XSAVES area
which fixed the bug too, but it's more efficient and cleaner to
initialize things once per boot, not for every signal handling
operation.
Reported-by: Kevin Hao <haokexin@xxxxxxxxx>
Reported-by: Joakim Tjernlund <Joakim.Tjernlund@xxxxxxxxxxxx>
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ravi V. Shankar <ravi.v.shankar@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: haokexin@xxxxxxxxx
Link: http://lkml.kernel.org/r/1485212084-4418-1-git-send-email-yu-cheng.yu@xxxxxxxxx
[ Combined it with 4c833368f0bf. ]
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/fpu/core.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -236,7 +236,8 @@ void fpstate_init(union fpregs_state *st
* it will #GP. Make sure it is replaced after the memset().
*/
if (static_cpu_has(X86_FEATURE_XSAVES))
- state->xsave.header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT;
+ state->xsave.header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT |
+ xfeatures_mask;
if (static_cpu_has(X86_FEATURE_FXSR))
fpstate_init_fxstate(&state->fxsave);
Patches currently in stable-queue which might be from yu-cheng.yu@xxxxxxxxx are
queue-4.9/x86-fpu-xstate-fix-xcomp_bv-in-xsaves-header.patch