From 53bbee3348d88b9f68946e249a67beaff82aee6a Mon Sep 17 00:00:00 2001
From: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Date: Mon, 21 Nov 2016 12:13:58 +0100
Subject: s390/vmlogrdr: fix IUCV buffer allocation

commit 5457e03de918f7a3e294eb9d26a608ab8a579976 upstream.

The buffer for iucv_message_receive() needs to be below 2 GB. In
__iucv_message_receive(), the buffer address is casted to an u32, which
would result in either memory corruption or an addressing exception when
using addresses >= 2 GB.

Fix this by using GFP_DMA for the buffer allocation.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/s390/char/vmlogrdr.c b/drivers/s390/char/vmlogrdr.c
index e883063..3167e85 100644
--- a/drivers/s390/char/vmlogrdr.c
+++ b/drivers/s390/char/vmlogrdr.c
@@ -870,7 +870,7 @@ static int __init vmlogrdr_init(void)
 		goto cleanup;
 
 	for (i=0; i < MAXMINOR; ++i ) {
-		sys_ser[i].buffer = (char *) get_zeroed_page(GFP_KERNEL);
+		sys_ser[i].buffer = (char *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
 		if (!sys_ser[i].buffer) {
 			rc = -ENOMEM;
 			break;
-- 
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