Patch "tap: double-free in error path in tap_open()" has been added to the 4.13-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

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

to the 4.13-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     tap-double-free-in-error-path-in-tap_open.patch
and it can be found in the queue-4.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Wed Nov 15 17:25:34 CET 2017
From: Girish Moodalbail <girish.moodalbail@oracle.com>
Date: Wed, 25 Oct 2017 00:23:04 -0700
Subject: tap: double-free in error path in tap_open()

From: Girish Moodalbail <girish.moodalbail@oracle.com>


[ Upstream commit 78e0ea6791d7baafb8a0ca82b1bd0c7b3453c919 ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/tap.c |   18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

--- a/drivers/net/tap.c
+++ b/drivers/net/tap.c
@@ -517,6 +517,10 @@ static int tap_open(struct inode *inode,
 					     &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,
 	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)


Patches currently in stable-queue which might be from girish.moodalbail@oracle.com are

queue-4.13/tap-reference-to-kva-of-an-unloaded-module-causes-kernel-panic.patch
queue-4.13/tap-double-free-in-error-path-in-tap_open.patch