This is a note to let you know that I've just added the patch titled
x86/fpu/xsaves: Fix improper uses of __ex_table
to the 3.19-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-xsaves-fix-improper-uses-of-__ex_table.patch
and it can be found in the queue-3.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 06c8173eb92bbfc03a0fe8bb64315857d0badd06 Mon Sep 17 00:00:00 2001
From: Quentin Casasnovas <[email protected]>
Date: Thu, 5 Mar 2015 13:19:22 +0100
Subject: x86/fpu/xsaves: Fix improper uses of __ex_table
From: Quentin Casasnovas <[email protected]>
commit 06c8173eb92bbfc03a0fe8bb64315857d0badd06 upstream.
Commit:
f31a9f7c7169 ("x86/xsaves: Use xsaves/xrstors to save and restore xsave area")
introduced alternative instructions for XSAVES/XRSTORS and commit:
adb9d526e982 ("x86/xsaves: Add xsaves and xrstors support for booting time")
added support for the XSAVES/XRSTORS instructions at boot time.
Unfortunately both failed to properly protect them against faulting:
The 'xstate_fault' macro will use the closest label named '1'
backward and that ends up in the .altinstr_replacement section
rather than in .text. This means that the kernel will never find
in the __ex_table the .text address where this instruction might
fault, leading to serious problems if userspace manages to
trigger the fault.
Signed-off-by: Quentin Casasnovas <[email protected]>
Signed-off-by: Jamie Iles <[email protected]>
[ Improved the changelog, fixed some whitespace noise. ]
Acked-by: Borislav Petkov <[email protected]>
Acked-by: Linus Torvalds <[email protected]>
Cc: Allan Xavier <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Fixes: adb9d526e982 ("x86/xsaves: Add xsaves and xrstors support for booting
time")
Fixes: f31a9f7c7169 ("x86/xsaves: Use xsaves/xrstors to save and restore xsave
area")
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/x86/include/asm/xsave.h | 28 +++++++++++-----------------
1 file changed, 11 insertions(+), 17 deletions(-)
--- a/arch/x86/include/asm/xsave.h
+++ b/arch/x86/include/asm/xsave.h
@@ -82,18 +82,15 @@ static inline int xsave_state_booting(st
if (boot_cpu_has(X86_FEATURE_XSAVES))
asm volatile("1:"XSAVES"\n\t"
"2:\n\t"
- : : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
+ xstate_fault
+ : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
: "memory");
else
asm volatile("1:"XSAVE"\n\t"
"2:\n\t"
- : : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
+ xstate_fault
+ : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
: "memory");
-
- asm volatile(xstate_fault
- : "0" (0)
- : "memory");
-
return err;
}
@@ -112,18 +109,15 @@ static inline int xrstor_state_booting(s
if (boot_cpu_has(X86_FEATURE_XSAVES))
asm volatile("1:"XRSTORS"\n\t"
"2:\n\t"
- : : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
+ xstate_fault
+ : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
: "memory");
else
asm volatile("1:"XRSTOR"\n\t"
"2:\n\t"
- : : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
+ xstate_fault
+ : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
: "memory");
-
- asm volatile(xstate_fault
- : "0" (0)
- : "memory");
-
return err;
}
@@ -149,9 +143,9 @@ static inline int xsave_state(struct xsa
*/
alternative_input_2(
"1:"XSAVE,
- "1:"XSAVEOPT,
+ XSAVEOPT,
X86_FEATURE_XSAVEOPT,
- "1:"XSAVES,
+ XSAVES,
X86_FEATURE_XSAVES,
[fx] "D" (fx), "a" (lmask), "d" (hmask) :
"memory");
@@ -178,7 +172,7 @@ static inline int xrstor_state(struct xs
*/
alternative_input(
"1: " XRSTOR,
- "1: " XRSTORS,
+ XRSTORS,
X86_FEATURE_XSAVES,
"D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
: "memory");
Patches currently in stable-queue which might be from
[email protected] are
queue-3.19/x86-fpu-xsaves-fix-improper-uses-of-__ex_table.patch
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