From 55441070ca1cbd47ce1ad2959bbf4b47aed9b83b Mon Sep 17 00:00:00 2001 From: Glenn Ruben Bakke Date: Fri, 22 Apr 2016 18:06:11 +0200 Subject: 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 Acked-by: Jukka Rissanen Signed-off-by: Marcel Holtmann Cc: stable@vger.kernel.org # 4.5+ --- net/bluetooth/6lowpan.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) (limited to 'net/bluetooth') diff --git a/net/bluetooth/6lowpan.c b/net/bluetooth/6lowpan.c index 38e82ddd7ccd..780089d75915 100644 --- a/net/bluetooth/6lowpan.c +++ b/net/bluetooth/6lowpan.c @@ -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; } -- cgit v1.2.3-55-g7522