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 4.4-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-4.4 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 @@ -150,7 +150,7 @@ 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-4.4/s390-uaccess-get_user-should-zero-on-failure-again.patch queue-4.4/s390-decompressor-fix-initrd-corruption-caused-by-bss-clear.patch