This is a note to let you know that I've just added the patch titled
microblaze: Fix /dev/zero corruption from __clear_user()
to the 2.6.38-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:
microblaze-fix-dev-zero-corruption-from-__clear_user.patch
and it can be found in the queue-2.6.38 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 6f3946b421395ff853bc0bcdab9c26b50ebbba8f Mon Sep 17 00:00:00 2001
From: Steven J. Magnani <[email protected]>
Date: Thu, 10 Feb 2011 12:12:13 -0600
Subject: microblaze: Fix /dev/zero corruption from __clear_user()
From: Steven J. Magnani <[email protected]>
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 <[email protected]>
Acked-by: Michal Simek <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/microblaze/include/asm/uaccess.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
--- a/arch/microblaze/include/asm/uaccess.h
+++ b/arch/microblaze/include/asm/uaccess.h
@@ -120,16 +120,16 @@ static inline unsigned long __must_check
{
/* 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;
}
Patches currently in stable-queue which might be from [email protected] are
queue-2.6.38/microblaze-fix-dev-zero-corruption-from-__clear_user.patch
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