Patch "Bluetooth: 6lowpan: Fix memory corruption of ipv6 destination address" has been added to the 4.5-stable tree

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

Bluetooth: 6lowpan: Fix memory corruption of ipv6 destination address

to the 4.5-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:
bluetooth-6lowpan-fix-memory-corruption-of-ipv6-destination-address.patch
and it can be found in the queue-4.5 subdirectory.

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

From: Glenn Ruben Bakke <[email protected]>
Date: Fri, 22 Apr 2016 18:06:11 +0200
Subject: Bluetooth: 6lowpan: Fix memory corruption of ipv6 destination address

From: Glenn Ruben Bakke <[email protected]>

commit 55441070ca1cbd47ce1ad2959bbf4b47aed9b83b upstream.

The memcpy of ipv6 header destination address to the skb control block (sbk->cb) in header_create() results in currupted memory when bt_xmit() is issued. The skb->cb is "released" in the return of header_create() making room for lower layer to minipulate the skb->cb.

The value retrieved in bt_xmit is not persistent across header creation and sending, and the lower layer will overwrite portions of skb->cb, making the copied destination address wrong.

The memory corruption will lead to non-working multicast as the first 4 bytes of the copied destination address is replaced by a value that resolves into a non-multicast prefix.

This fix removes the dependency on the skb control block between header creation and send, by moving the destination address memcpy to the send function path (setup_create, which is called from bt_xmit).

---
 net/bluetooth/6lowpan.c |   11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

@@ -431,15 +431,18 @@ static int setup_header(struct sk_buff *
 			bdaddr_t *peer_addr, u8 *peer_addr_type)
 {
 	struct in6_addr ipv6_daddr;
+	struct ipv6hdr *hdr;
 	struct lowpan_dev *dev;
 	struct lowpan_peer *peer;
 	bdaddr_t addr, *any = BDADDR_ANY;
 	u8 *daddr = any->b;
 	int err, status = 0;
 
+	hdr = ipv6_hdr(skb);
+
 	dev = lowpan_dev(netdev);
 
-	memcpy(&ipv6_daddr, &lowpan_cb(skb)->addr, sizeof(ipv6_daddr));
+	memcpy(&ipv6_daddr, &hdr->daddr, sizeof(ipv6_daddr));
 
 	if (ipv6_addr_is_multicast(&ipv6_daddr)) {
 		lowpan_cb(skb)->chan = NULL;

@@ -489,15 +492,9 @@ static int header_create(struct sk_buff
 			 unsigned short type, const void *_daddr,
 			 const void *_saddr, unsigned int len)
 {
-	struct ipv6hdr *hdr;
-
 	if (type != ETH_P_IPV6)
 		return -EINVAL;
 
-	hdr = ipv6_hdr(skb);
-
-	memcpy(&lowpan_cb(skb)->addr, &hdr->daddr, sizeof(struct in6_addr));
-
 	return 0;
 }
 

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

queue-4.5/bluetooth-6lowpan-fix-memory-corruption-of-ipv6-destination-address.patch