linux-kernel - [PATCH stable-4.9.y] locking/qspinlock: Pull in asm/byteorder.h to ensure correct endianness

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 24 Jan 2019 18:54:15 +0000
From:   Will Deacon <will.deacon@....com>
To:     gregkh@...uxfoundation.org
Cc:     linux-kernel@...r.kernel.org, Dave Airlie <airlied@...hat.com>,
        stable@...r.kernel.org, Will Deacon <will.deacon@....com>
Subject: [PATCH stable-4.9.y] locking/qspinlock: Pull in asm/byteorder.h to ensure correct endianness

From: Dave Airlie <airlied@...hat.com>

This commit is not required upstream, but is required for the 4.9.y
stable series.

Upstream commit 101110f6271c ("Kbuild: always define endianess in
kconfig.h") ensures that either __LITTLE_ENDIAN or __BIG_ENDIAN is
defined to reflect the endianness of the target CPU architecture
regardless of whether or not <asm/byteorder.h> has been #included. The
upstream definition of 'struct qspinlock' relies on this property.

Unfortunately, the 4.9.y stable series does not provide this guarantee,
so the 'spin_unlock()' routine can erroneously treat the underlying
lockword as big-endian on little-endian architectures using native
qspinlock (i.e. x86_64 without PV) if the caller has not included
<asm/byteorder.h>. This can lead to hangs such as the one in
'i915_gem_request()' reported via bugzilla:

  https://bugzilla.kernel.org/show_bug.cgi?id=202063

Fix the issue by ensuring that <asm/byteorder.h> is #included in
<asm/qspinlock_types.h>, where 'struct qspinlock' is defined.

Cc: <stable@...r.kernel.org> # 4.9
Signed-off-by: Dave Airlie <airlied@...hat.com>
[will: wrote commit message]
Signed-off-by: Will Deacon <will.deacon@....com>
---
 include/asm-generic/qspinlock_types.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/asm-generic/qspinlock_types.h b/include/asm-generic/qspinlock_types.h
index d10f1e7d6ba8..6503e96710fa 100644
--- a/include/asm-generic/qspinlock_types.h
+++ b/include/asm-generic/qspinlock_types.h
@@ -18,6 +18,8 @@
 #ifndef __ASM_GENERIC_QSPINLOCK_TYPES_H
 #define __ASM_GENERIC_QSPINLOCK_TYPES_H

+#include <asm/byteorder.h>
+
 /*
  * Including atomic.h with PARAVIRT on will cause compilation errors because
  * of recursive header file incluson via paravirt_types.h. So don't include
-- 
2.17.1