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List:       linux-stable-commits
Subject:    Patch "x86-32, espfix: Remove filter for espfix32 due to race" has been added to the 3.15-stable tre
From:       <gregkh () linuxfoundation ! org>
Date:       2014-06-28 1:14:27
Message-ID: 1403918067426 () kroah ! com
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This is a note to let you know that I've just added the patch titled

    x86-32, espfix: Remove filter for espfix32 due to race

to the 3.15-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:
     x86-32-espfix-remove-filter-for-espfix32-due-to-race.patch
and it can be found in the queue-3.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From 246f2d2ee1d715e1077fc47d61c394569c8ee692 Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa@linux.intel.com>
Date: Wed, 30 Apr 2014 14:03:25 -0700
Subject: x86-32, espfix: Remove filter for espfix32 due to race

From: "H. Peter Anvin" <hpa@linux.intel.com>

commit 246f2d2ee1d715e1077fc47d61c394569c8ee692 upstream.

It is not safe to use LAR to filter when to go down the espfix path,
because the LDT is per-process (rather than per-thread) and another
thread might change the descriptors behind our back.  Fortunately it
is always *safe* (if a bit slow) to go down the espfix path, and a
32-bit LDT stack segment is extremely rare.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1398816946-3351-1-git-send-email-hpa@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/kernel/entry_32.S |    5 -----
 1 file changed, 5 deletions(-)

--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -551,11 +551,6 @@ ENTRY(iret_exc)
 
 	CFI_RESTORE_STATE
 ldt_ss:
-	larl PT_OLDSS(%esp), %eax
-	jnz restore_nocheck
-	testl $0x00400000, %eax		# returning to 32bit stack?
-	jnz restore_nocheck		# allright, normal return
-
 #ifdef CONFIG_PARAVIRT
 	/*
 	 * The kernel can't run on a non-flat stack if paravirt mode


Patches currently in stable-queue which might be from hpa@linux.intel.com are

queue-3.15/x86-32-espfix-remove-filter-for-espfix32-due-to-race.patch
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