[3.19.y-ckt stable] Patch "s390/compat: correct restore of high gprs on signal return" has been added to the 3.19.y-ckt tree

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    s390/compat: correct restore of high gprs on signal return

to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue

This patch is scheduled to be released in version 3.19.8-ckt16.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

>From 4c15538a2cbeb0ca180f177e40095f5bf681fd21 Mon Sep 17 00:00:00 2001
From: Martin Schwidefsky <schwidefsky at de.ibm.com>
Date: Fri, 19 Feb 2016 14:44:14 +0100
Subject: s390/compat: correct restore of high gprs on signal return

commit 342300cc9cd3428bc6bfe5809bfcc1b9a0f06702 upstream.

git commit 8070361799ae1e3f4ef347bd10f0a508ac10acfb
"s390: add support for vector extension"
broke 31-bit compat processes in regard to signal handling.

The restore_sigregs_ext32() function is used to restore the additional
elements from the user space signal frame. Among the additional elements
are the upper registers halves for 64-bit register support for 31-bit
processes. The copy_from_user that is used to retrieve the high-gprs
array from the user stack uses an incorrect length, 8 bytes instead of
64 bytes. This causes incorrect upper register halves to get loaded.

Signed-off-by: Martin Schwidefsky <schwidefsky at de.ibm.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 arch/s390/kernel/compat_signal.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/s390/kernel/compat_signal.c b/arch/s390/kernel/compat_signal.c
index f564740..020e872 100644
--- a/arch/s390/kernel/compat_signal.c
+++ b/arch/s390/kernel/compat_signal.c
@@ -293,7 +293,7 @@ static int restore_sigregs_ext32(struct pt_regs *regs,

 	/* Restore high gprs from signal stack */
 	if (__copy_from_user(&gprs_high, &sregs_ext->gprs_high,
-			     sizeof(&sregs_ext->gprs_high)))
+			     sizeof(sregs_ext->gprs_high)))
 		return -EFAULT;
 	for (i = 0; i < NUM_GPRS; i++)
 		*(__u32 *)&regs->gprs[i] = gprs_high[i];
--
2.7.0