This is a note to let you know that I've just added the patch titled
x86/mpx: Fix instruction decoder condition
to the 4.1-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-mpx-fix-instruction-decoder-condition.patch
and it can be found in the queue-4.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 8e8efe0379bd93e8219ca0fc6fa80b5dd85b09cb Mon Sep 17 00:00:00 2001
From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Date: Mon, 30 Nov 2015 16:31:13 -0800
Subject: x86/mpx: Fix instruction decoder condition
From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
commit 8e8efe0379bd93e8219ca0fc6fa80b5dd85b09cb upstream.
MPX decodes instructions in order to tell which bounds register
was violated. Part of this decoding involves looking at the "REX
prefix" which is a special instrucion prefix used to retrofit
support for new registers in to old instructions.
The X86_REX_*() macros are defined to return actual bit values:
#define X86_REX_R(rex) ((rex) & 4)
*not* boolean values. However, the MPX code was checking for
them like they were booleans. This might have led to us
mis-decoding the "REX prefix" and giving false information out to
userspace about bounds violations. X86_REX_B() actually is bit 1,
so this is really only broken for the X86_REX_X() case.
Fix the conditionals up to tolerate the non-boolean values.
Fixes: fcc7ffd67991 "x86, mpx: Decode MPX instruction to get bound violation information"
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: Dave Hansen <dave@xxxxxxxx>
Link: http://lkml.kernel.org/r/20151201003113.D800C1E0@xxxxxxxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/mm/mpx.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -120,19 +120,19 @@ static int get_reg_offset(struct insn *i
switch (type) {
case REG_TYPE_RM:
regno = X86_MODRM_RM(insn->modrm.value);
- if (X86_REX_B(insn->rex_prefix.value) == 1)
+ if (X86_REX_B(insn->rex_prefix.value))
regno += 8;
break;
case REG_TYPE_INDEX:
regno = X86_SIB_INDEX(insn->sib.value);
- if (X86_REX_X(insn->rex_prefix.value) == 1)
+ if (X86_REX_X(insn->rex_prefix.value))
regno += 8;
break;
case REG_TYPE_BASE:
regno = X86_SIB_BASE(insn->sib.value);
- if (X86_REX_B(insn->rex_prefix.value) == 1)
+ if (X86_REX_B(insn->rex_prefix.value))
regno += 8;
break;
Patches currently in stable-queue which might be from dave.hansen@xxxxxxxxxxxxxxx are
queue-4.1/x86-mm-add-barriers-and-document-switch_mm-vs-flush-synchronization.patch
queue-4.1/x86-mm-improve-switch_mm-barrier-comments.patch
queue-4.1/x86-mpx-fix-instruction-decoder-condition.patch
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