[3.16.y-ckt stable] Patch "connector: bump skb->users before callback invocation" has been added to the 3.16.y-ckt tree

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    connector: bump skb->users before callback invocation

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt24.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

---8<------------------------------------------------------------

>From c6ebbea289e909e6e65c5050a2bb74c64748b65d Mon Sep 17 00:00:00 2001
From: Florian Westphal <fw at strlen.de>
Date: Thu, 31 Dec 2015 14:26:33 +0100
Subject: connector: bump skb->users before callback invocation

commit 55285bf09427c5abf43ee1d54e892f352092b1f1 upstream.

Dmitry reports memleak with syskaller program.
Problem is that connector bumps skb usecount but might not invoke callback.

So move skb_get to where we invoke the callback.

Reported-by: Dmitry Vyukov <dvyukov at google.com>
Signed-off-by: Florian Westphal <fw at strlen.de>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/connector/connector.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/drivers/connector/connector.c b/drivers/connector/connector.c
index f612d68629dc..fd7430e30cbc 100644
--- a/drivers/connector/connector.c
+++ b/drivers/connector/connector.c
@@ -172,26 +172,21 @@ static int cn_call_callback(struct sk_buff *skb)
  *
  * It checks skb, netlink header and msg sizes, and calls callback helper.
  */
-static void cn_rx_skb(struct sk_buff *__skb)
+static void cn_rx_skb(struct sk_buff *skb)
 {
 	struct nlmsghdr *nlh;
-	struct sk_buff *skb;
 	int len, err;

-	skb = skb_get(__skb);
-
 	if (skb->len >= NLMSG_HDRLEN) {
 		nlh = nlmsg_hdr(skb);
 		len = nlmsg_len(nlh);

 		if (len < (int)sizeof(struct cn_msg) ||
 		    skb->len < nlh->nlmsg_len ||
-		    len > CONNECTOR_MAX_MSG_SIZE) {
-			kfree_skb(skb);
+		    len > CONNECTOR_MAX_MSG_SIZE)
 			return;
-		}

-		err = cn_call_callback(skb);
+		err = cn_call_callback(skb_get(skb));
 		if (err < 0)
 			kfree_skb(skb);
 	}