[PATCH 4.4 25/47] 9p: fix multiple NULL-pointer-dereferences

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Tomas Bortoli <tomasbortoli@xxxxxxxxx>

commit 10aa14527f458e9867cf3d2cc6b8cb0f6704448b upstream.

Added checks to prevent GPFs from raising.

Link: http://lkml.kernel.org/r/20180727110558.5479-1-tomasbortoli@xxxxxxxxx
Signed-off-by: Tomas Bortoli <tomasbortoli@xxxxxxxxx>
Reported-by: syzbot+1a262da37d3bead15c39@xxxxxxxxxxxxxxxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Dominique Martinet <dominique.martinet@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 net/9p/trans_fd.c     |    5 ++++-
 net/9p/trans_rdma.c   |    3 +++
 net/9p/trans_virtio.c |    3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)

--- a/net/9p/trans_fd.c
+++ b/net/9p/trans_fd.c
@@ -935,7 +935,7 @@ p9_fd_create_tcp(struct p9_client *clien
 	if (err < 0)
 		return err;
 
-	if (valid_ipaddr4(addr) < 0)
+	if (addr == NULL || valid_ipaddr4(addr) < 0)
 		return -EINVAL;
 
 	csocket = NULL;
@@ -983,6 +983,9 @@ p9_fd_create_unix(struct p9_client *clie
 
 	csocket = NULL;
 
+	if (addr == NULL)
+		return -EINVAL;
+
 	if (strlen(addr) >= UNIX_PATH_MAX) {
 		pr_err("%s (%d): address too long: %s\n",
 		       __func__, task_pid_nr(current), addr);
--- a/net/9p/trans_rdma.c
+++ b/net/9p/trans_rdma.c
@@ -644,6 +644,9 @@ rdma_create_trans(struct p9_client *clie
 	struct ib_qp_init_attr qp_attr;
 	struct ib_cq_init_attr cq_attr = {};
 
+	if (addr == NULL)
+		return -EINVAL;
+
 	/* Parse the transport specific mount options */
 	err = parse_opts(args, &opts);
 	if (err < 0)
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -654,6 +654,9 @@ p9_virtio_create(struct p9_client *clien
 	int ret = -ENOENT;
 	int found = 0;
 
+	if (devname == NULL)
+		return -EINVAL;
+
 	mutex_lock(&virtio_9p_lock);
 	list_for_each_entry(chan, &virtio_chan_list, chan_list) {
 		if (!strncmp(devname, chan->tag, chan->tag_len) &&