Patch "s390/chsc: Add exception handler for CHSC instruction" has been added to the 4.9-stable tree

Patch "s390/chsc: Add exception handler for CHSC instruction" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    s390/chsc: Add exception handler for CHSC instruction

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-chsc-add-exception-handler-for-chsc-instruction.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@vger.kernel.org> know about it.


>From 77759137248f34864a8f7a58bbcebfcf1047504a Mon Sep 17 00:00:00 2001
From: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Date: Mon, 20 Feb 2017 14:52:58 +0100
Subject: s390/chsc: Add exception handler for CHSC instruction

From: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>

commit 77759137248f34864a8f7a58bbcebfcf1047504a upstream.

Prevent kernel crashes due to unhandled exceptions raised by the CHSC
instruction which may for example be triggered by invalid ioctl data.

Fixes: 64150adf89df ("s390/cio: Introduce generic synchronous CHSC IOCTL")
Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Reviewed-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/s390/cio/ioasm.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/drivers/s390/cio/ioasm.c
+++ b/drivers/s390/cio/ioasm.c
@@ -165,13 +165,15 @@ int tpi(struct tpi_info *addr)
 int chsc(void *chsc_area)
 {
 	typedef struct { char _[4096]; } addr_type;
-	int cc;
+	int cc = -EIO;
 
 	asm volatile(
 		"	.insn	rre,0xb25f0000,%2,0\n"
-		"	ipm	%0\n"
+		"0:	ipm	%0\n"
 		"	srl	%0,28\n"
-		: "=d" (cc), "=m" (*(addr_type *) chsc_area)
+		"1:\n"
+		EX_TABLE(0b, 1b)
+		: "+d" (cc), "=m" (*(addr_type *) chsc_area)
 		: "d" (chsc_area), "m" (*(addr_type *) chsc_area)
 		: "cc");
 	trace_s390_cio_chsc(chsc_area, cc);


Patches currently in stable-queue which might be from oberpar@linux.vnet.ibm.com are

queue-4.9/s390-chsc-add-exception-handler-for-chsc-instruction.patch