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authorSteven J. Magnani <steve@digidescorp.com>2011-02-10 12:12:13 -0600
committerGreg Kroah-Hartman <gregkh@suse.de>2011-03-23 13:03:39 -0700
commit1bb392f30a34dfb18d72750fd9898f71b9ed7923 (patch)
tree9174840e7f7b6d5119d78964514ac895d73fccee /arch
parentb030eac99b99ba92dd6d3bcf641c3fa219b2a73e (diff)
downloadlinux-2.6.38-lt-ux500-1bb392f30a34dfb18d72750fd9898f71b9ed7923.tar.gz
microblaze: Fix /dev/zero corruption from __clear_user()
commit 6f3946b421395ff853bc0bcdab9c26b50ebbba8f upstream. A userland read of more than PAGE_SIZE bytes from /dev/zero results in (a) not all of the bytes returned being zero, and (b) memory corruption due to zeroing of bytes beyond the user buffer. This is caused by improper constraints on the assembly __clear_user function. The constrints don't indicate to the compiler that the pointer argument is modified. Since the function is inline, this results in double-incrementing of the pointer when __clear_user() is invoked through a multi-page read() of /dev/zero. Signed-off-by: Steven J. Magnani <steve@digidescorp.com> Acked-by: Michal Simek <monstr@monstr.eu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'arch')
-rw-r--r--arch/microblaze/include/asm/uaccess.h8
1 files changed, 4 insertions, 4 deletions
diff --git a/arch/microblaze/include/asm/uaccess.h b/arch/microblaze/include/asm/uaccess.h
index d840f4a2d3c..5bb95a11880 100644
--- a/arch/microblaze/include/asm/uaccess.h
+++ b/arch/microblaze/include/asm/uaccess.h
@@ -120,16 +120,16 @@ static inline unsigned long __must_check __clear_user(void __user *to,
{
/* normal memset with two words to __ex_table */
__asm__ __volatile__ ( \
- "1: sb r0, %2, r0;" \
+ "1: sb r0, %1, r0;" \
" addik %0, %0, -1;" \
" bneid %0, 1b;" \
- " addik %2, %2, 1;" \
+ " addik %1, %1, 1;" \
"2: " \
__EX_TABLE_SECTION \
".word 1b,2b;" \
".previous;" \
- : "=r"(n) \
- : "0"(n), "r"(to)
+ : "=r"(n), "=r"(to) \
+ : "0"(n), "1"(to)
);
return n;
}