From 75dd32a185871fead13cd3586e00980b35410ff0 Mon Sep 17 00:00:00 2001
From: Zhilong Liu <zlliu@suse.com>
Date: Mon, 20 Mar 2017 13:21:41 +0800
Subject: [RHEL7.5 PATCH 014/169] mdadm/Monitor: Fix NULL pointer
 dereference when stat2devnm return NULL

Wait(): stat2devnm() returns NULL for non block devices. Check the
pointer is valid derefencing it. This can happen when using --wait,
such as the 'f' and 'd' file type, causing a core dump.
such as: ./mdadm --wait /dev/md/

Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: Zhilong Liu <zlliu@suse.com>
Signed-off-by: Jes Sorensen <Jes.Sorensen@gmail.com>
---
 Monitor.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/Monitor.c b/Monitor.c
index 802a9d9..bdd3e63 100644
--- a/Monitor.c
+++ b/Monitor.c
@@ -994,6 +994,7 @@ int Wait(char *dev)
 {
 	struct stat stb;
 	char devnm[32];
+	char *tmp;
 	int rv = 1;
 	int frozen_remaining = 3;
 
@@ -1002,7 +1003,12 @@ int Wait(char *dev)
 			strerror(errno));
 		return 2;
 	}
-	strcpy(devnm, stat2devnm(&stb));
+	tmp = stat2devnm(&stb);
+	if (!tmp) {
+		pr_err("%s is not a block device.\n", dev);
+		return 2;
+	}
+	strcpy(devnm, tmp);
 
 	while(1) {
 		struct mdstat_ent *ms = mdstat_read(1, 0);
-- 
2.7.4