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List:       git-commits-head
Subject:    [ARM] 4837/1: make __get_unaligned_*() return unsigned types
From:       Linux Kernel Mailing List <linux-kernel () vger ! kernel ! org>
Date:       2008-03-01 0:59:03
Message-ID: 200803010059.m210x3sZ031592 () hera ! kernel ! org
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Gitweb:     http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=94a3f78566ef98a48814d82892f28bb741624cb8
Commit:     94a3f78566ef98a48814d82892f28bb741624cb8
Parent:     b98d7291883f7ed27e3f4b59bc12dc963c9f72a6
Author:     Lennert Buytenhek <buytenh@wantstofly.org>
AuthorDate: Sat Feb 23 00:23:48 2008 +0100
Committer:  Russell King <rmk+kernel@arm.linux.org.uk>
CommitDate: Fri Feb 29 22:46:48 2008 +0000

    [ARM] 4837/1: make __get_unaligned_*() return unsigned types
    
    Eric Sandeen tracked an XFS on ARM corruption bug down to a function
    under fs/xfs/ involving some get_unaligned() calls on u64 pointers.
    As it turns out, calling ARM's get_unaligned() on a u64 pointer
    pointing to the following byte sequence:
    
    	80 81 82 83 84 85 86 87
    
    would return ffffffff83828180 (LE mode.)  This turns out to be
    because of implicit u8 -> int promotion in ARM's implementation of
    various helpers for get_unaligned(), causing them to accidentally
    return signed instead of unsigned values, which in turn caused the
    subsequent casts to unsigned long long in __get_unaligned_8_[bl]e()
    to sign-extend the lower words.
    
    Fix by casting the return values of __get_unaligned_[24]_[bl]e()
    to unsigned int.
    
    Cc: Eric Sandeen <sandeen@sandeen.net>
    Cc: Rabeeh Khoury <rabeeh@marvell.com>
    Cc: Nicolas Pitre <nico@marvell.com>
    Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
    Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
 include/asm-arm/unaligned.h |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/asm-arm/unaligned.h b/include/asm-arm/unaligned.h
index 8431f6e..5db03cf 100644
--- a/include/asm-arm/unaligned.h
+++ b/include/asm-arm/unaligned.h
@@ -40,16 +40,16 @@ extern int __bug_unaligned_x(const void *ptr);
  */
 
 #define __get_unaligned_2_le(__p)					\
-	(__p[0] | __p[1] << 8)
+	(unsigned int)(__p[0] | __p[1] << 8)
 
 #define __get_unaligned_2_be(__p)					\
-	(__p[0] << 8 | __p[1])
+	(unsigned int)(__p[0] << 8 | __p[1])
 
 #define __get_unaligned_4_le(__p)					\
-	(__p[0] | __p[1] << 8 | __p[2] << 16 | __p[3] << 24)
+	(unsigned int)(__p[0] | __p[1] << 8 | __p[2] << 16 | __p[3] << 24)
 
 #define __get_unaligned_4_be(__p)					\
-	(__p[0] << 24 | __p[1] << 16 | __p[2] << 8 | __p[3])
+	(unsigned int)(__p[0] << 24 | __p[1] << 16 | __p[2] << 8 | __p[3])
 
 #define __get_unaligned_8_le(__p)					\
 	((unsigned long long)__get_unaligned_4_le((__p+4)) << 32 |	\
--
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