[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>

diff --git a/include/asm-arm/unaligned.h b/include/asm-arm/unaligned.h
index 8431f6e..5db03cf 100644 (file)
--- 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 |      \