Patch "netlink: Fix dump skb leak/double free" has been added to the 4.6-stable tree

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

netlink: Fix dump skb leak/double free

to the 4.6-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:
netlink-fix-dump-skb-leak-double-free.patch
and it can be found in the queue-4.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Herbert Xu <[email protected]>
Date: Mon, 16 May 2016 17:28:16 +0800
Subject: netlink: Fix dump skb leak/double free

From: Herbert Xu <[email protected]>

[ Upstream commit 92964c79b357efd980812c4de5c1fd2ec8bb5520 ]

When we free cb->skb after a dump, we do it after releasing the lock. This means that a new dump could have started in the time being and we'll end up freeing their skb instead of ours.

This patch saves the skb and module before we unlock so we free the right memory.

---
 net/netlink/af_netlink.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

@@ -2059,6 +2059,7 @@ static int netlink_dump(struct sock *sk)
 	struct netlink_callback *cb;
 	struct sk_buff *skb = NULL;
 	struct nlmsghdr *nlh;
+	struct module *module;
 	int len, err = -ENOBUFS;
 	int alloc_min_size;
 	int alloc_size;

@@ -2134,9 +2135,11 @@ static int netlink_dump(struct sock *sk)
 		cb->done(cb);
 
 	nlk->cb_running = false;
+	module = cb->module;
+	skb = cb->skb;
 	mutex_unlock(nlk->cb_mutex);
-	module_put(cb->module);
-	consume_skb(cb->skb);
+	module_put(module);
+	consume_skb(skb);
 	return 0;
 
 errout_skb:

Patches currently in stable-queue which might be from [email protected] are

queue-4.6/netlink-fix-dump-skb-leak-double-free.patch