netdev - [PATCH] libceph: potential NULL dereference in ceph_msg_data

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Date:   Mon, 17 Jul 2017 11:13:35 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Ilya Dryomov <idryomov@...il.com>, Alex Elder <elder@...tank.com>
Cc:     "Yan, Zheng" <zyan@...hat.com>, Sage Weil <sage@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        ceph-devel@...r.kernel.org, netdev@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: [PATCH] libceph: potential NULL dereference in ceph_msg_data_create()

If kmem_cache_zalloc() returns NULL then the INIT_LIST_HEAD(&data->links);
will Oops.  The callers aren't really prepared for NULL returns so it
doesn't make a lot of difference in real life.

Fixes: 5240d9f95dfe ("libceph: replace message data pointer with list")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>

diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 0c31035bbfee..b7cc615d42ef 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -3203,8 +3203,10 @@ static struct ceph_msg_data *ceph_msg_data_create(enum ceph_msg_data_type type)
 		return NULL;
 
 	data = kmem_cache_zalloc(ceph_msg_data_cache, GFP_NOFS);
-	if (data)
-		data->type = type;
+	if (!data)
+		return NULL;
+
+	data->type = type;
 	INIT_LIST_HEAD(&data->links);
 
 	return data;