ocfs2: avoid possible NULL pointer dereference in o2net_accept_one()

Since o2nm_get_node_by_num() may return NULL, we add this check in
o2net_accept_one() to avoid possible NULL pointer dereference.

Signed-off-by: Joseph Qi <joseph.qi@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 6 deletions

diff --git a/fs/ocfs2/cluster/tcp.c b/fs/ocfs2/cluster/tcp.c
index 8c50c238577a..2cd2406b4140 100644
--- a/fs/ocfs2/cluster/tcp.c
+++ b/fs/ocfs2/cluster/tcp.c
@@ -1873,12 +1873,16 @@ static int o2net_accept_one(struct socket *sock)
 
         if (o2nm_this_node() >= node->nd_num) {
                 local_node = o2nm_get_node_by_num(o2nm_this_node());
-                printk(KERN_NOTICE "o2net: Unexpected connect attempt seen "
-                       "at node '%s' (%u, %pI4:%d) from node '%s' (%u, "
-                       "%pI4:%d)\n", local_node->nd_name, local_node->nd_num,
-                       &(local_node->nd_ipv4_address),
-                       ntohs(local_node->nd_ipv4_port), node->nd_name,
-                       node->nd_num, &sin.sin_addr.s_addr, ntohs(sin.sin_port));
+                if (local_node)
+                        printk(KERN_NOTICE "o2net: Unexpected connect attempt "
+                                        "seen at node '%s' (%u, %pI4:%d) from "
+                                        "node '%s' (%u, %pI4:%d)\n",
+                                        local_node->nd_name, local_node->nd_num,
+                                        &(local_node->nd_ipv4_address),
+                                        ntohs(local_node->nd_ipv4_port),
+                                        node->nd_name,
+                                        node->nd_num, &sin.sin_addr.s_addr,
+                                        ntohs(sin.sin_port));
                 ret = -EINVAL;
                 goto out;
         }