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+
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@ -434,15 +434,18 @@ static int setup_header(struct sk_buff *skb, struct net_device *netdev,
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bdaddr_t *peer_addr, u8 *peer_addr_type)
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{
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struct in6_addr ipv6_daddr;
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struct ipv6hdr *hdr;
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struct lowpan_btle_dev *dev;
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struct lowpan_peer *peer;
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bdaddr_t addr, *any = BDADDR_ANY;
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u8 *daddr = any->b;
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int err, status = 0;
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hdr = ipv6_hdr(skb);
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dev = lowpan_btle_dev(netdev);
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memcpy(&ipv6_daddr, &lowpan_cb(skb)->addr, sizeof(ipv6_daddr));
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memcpy(&ipv6_daddr, &hdr->daddr, sizeof(ipv6_daddr));
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if (ipv6_addr_is_multicast(&ipv6_daddr)) {
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lowpan_cb(skb)->chan = NULL;
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@ -492,15 +495,9 @@ static int header_create(struct sk_buff *skb, struct net_device *netdev,
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unsigned short type, const void *_daddr,
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const void *_saddr, unsigned int len)
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{
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struct ipv6hdr *hdr;
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if (type != ETH_P_IPV6)
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return -EINVAL;
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hdr = ipv6_hdr(skb);
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memcpy(&lowpan_cb(skb)->addr, &hdr->daddr, sizeof(struct in6_addr));
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return 0;
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}
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