This is a note to let you know that I've just added the patch titled
s390/uaccess: get_user() should zero on failure (again)
to the 4.9-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:
s390-uaccess-get_user-should-zero-on-failure-again.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From d09c5373e8e4eaaa09233552cbf75dc4c4f21203 Mon Sep 17 00:00:00 2001
From: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Date: Mon, 27 Mar 2017 09:48:04 +0200
Subject: s390/uaccess: get_user() should zero on failure (again)
From: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
commit d09c5373e8e4eaaa09233552cbf75dc4c4f21203 upstream.
Commit fd2d2b191fe7 ("s390: get_user() should zero on failure")
intended to fix s390's get_user() implementation which did not zero
the target operand if the read from user space faulted. Unfortunately
the patch has no effect: the corresponding inline assembly specifies
that the operand is only written to ("=") and the previous value is
discarded.
Therefore the compiler is free to and actually does omit the zero
initialization.
To fix this simply change the contraint modifier to "+", so the
compiler cannot omit the initialization anymore.
Fixes: c9ca78415ac1 ("s390/uaccess: provide inline variants of get_user/put_user")
Fixes: fd2d2b191fe7 ("s390: get_user() should zero on failure")
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/s390/include/asm/uaccess.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/s390/include/asm/uaccess.h
+++ b/arch/s390/include/asm/uaccess.h
@@ -144,7 +144,7 @@ unsigned long __must_check __copy_to_use
" jg 2b\n" \
".popsection\n" \
EX_TABLE(0b,3b) EX_TABLE(1b,3b) \
- : "=d" (__rc), "=Q" (*(to)) \
+ : "=d" (__rc), "+Q" (*(to)) \
: "d" (size), "Q" (*(from)), \
"d" (__reg0), "K" (-EFAULT) \
: "cc"); \
Patches currently in stable-queue which might be from heiko.carstens@xxxxxxxxxx are
queue-4.9/s390-uaccess-get_user-should-zero-on-failure-again.patch
queue-4.9/s390-decompressor-fix-initrd-corruption-caused-by-bss-clear.patch