Commit 55441070 authored Apr 22, 2016 by Glenn Ruben Bakke Committed by Marcel Holtmann Apr 26, 2016

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



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).

Signed-off-by: Glenn Ruben Bakke <glenn.ruben.bakke@nordicsemi.no>
Acked-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Cc: stable@vger.kernel.org # 4.5+

parent 5c0e03cd

net/bluetooth/6lowpan.c

+4 −7

Original line number	Diff line number	Diff line
		@@ -434,15 +434,18 @@ static int setup_header(struct sk_buff skb, struct net_device netdev,
		bdaddr_t peer_addr, u8 peer_addr_type)
		{
		struct in6_addr ipv6_daddr;
		struct ipv6hdr *hdr;
		struct lowpan_btle_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_btle_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;
		@@ -492,15 +495,9 @@ static int header_create(struct sk_buff skb, struct net_device netdev,
		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;
		}