tap: double-free in error path in tap_open()

Double free of skb_array in tap module is causing kernel panic. When
tap_set_queue() fails we free skb_array right away by calling
skb_array_cleanup(). However, later on skb_array_cleanup() is called
again by tap_sock_destruct through sock_put(). This patch fixes that
issue.

Fixes: 362899b8725b35e3 (macvtap: switch to use skb array)
Signed-off-by: Girish Moodalbail <girish.moodalbail@oracle.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 9 deletions

diff --git a/drivers/net/tap.c b/drivers/net/tap.c
index 21b71ae947fd..98ee6cc2875d 100644
--- a/drivers/net/tap.c
+++ b/drivers/net/tap.c
@@ -517,6 +517,10 @@ static int tap_open(struct inode *inode, struct file *file)
                                              &tap_proto, 0);
         if (!q)
                 goto err;
+        if (skb_array_init(&q->skb_array, tap->dev->tx_queue_len, GFP_KERNEL)) {
+                sk_free(&q->sk);
+                goto err;
+        }
 
         RCU_INIT_POINTER(q->sock.wq, &q->wq);
         init_waitqueue_head(&q->wq.wait);
@@ -540,22 +544,18 @@ static int tap_open(struct inode *inode, struct file *file)
         if ((tap->dev->features & NETIF_F_HIGHDMA) && (tap->dev->features & NETIF_F_SG))
                 sock_set_flag(&q->sk, SOCK_ZEROCOPY);
 
-        err = -ENOMEM;
-        if (skb_array_init(&q->skb_array, tap->dev->tx_queue_len, GFP_KERNEL))
-                goto err_array;
-
         err = tap_set_queue(tap, file, q);
-        if (err)
-                goto err_queue;
+        if (err) {
+                /* tap_sock_destruct() will take care of freeing skb_array */
+                goto err_put;
+        }
 
         dev_put(tap->dev);
 
         rtnl_unlock();
         return err;
 
-err_queue:
-        skb_array_cleanup(&q->skb_array);
-err_array:
+err_put:
         sock_put(&q->sk);
 err:
         if (tap)