From: Michael Scott <michael@xxxxxxxxxxxxxxxxxxxxxxx> [ Upstream commit 03bc05e1a4972f73b4eb8907aa373369e825c252 ] After decompression of 6lowpan socket data, an IPv6 header is inserted before the existing socket payload. After this, we reset the network_header value of the skb to account for the difference in payload size from prior to decompression + the addition of the IPv6 header. However, we fail to reset the mac_header value. Leaving the mac_header value untouched here, can cause a calculation error in net/packet/af_packet.c packet_rcv() function when an AF_PACKET socket is opened in SOCK_RAW mode for use on a 6lowpan interface. On line 2088, the data pointer is moved backward by the value returned from skb_mac_header(). If skb->data is adjusted so that it is before the skb->head pointer (which can happen when an old value of mac_header is left in place) the kernel generates a panic in net/core/skbuff.c line 1717. This panic can be generated by BLE 6lowpan interfaces (such as bt0) and 802.15.4 interfaces (such as lowpan0) as they both use the same 6lowpan sources for compression and decompression. Signed-off-by: Michael Scott <michael@xxxxxxxxxxxxxxxxxxxxxxx> Acked-by: Alexander Aring <aring@xxxxxxxxxxxx> Acked-by: Jukka Rissanen <jukka.rissanen@xxxxxxxxxxxxxxx> Signed-off-by: Marcel Holtmann <marcel@xxxxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> --- net/6lowpan/iphc.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/6lowpan/iphc.c b/net/6lowpan/iphc.c index 79f1fa22509a..23654f1902f3 100644 --- a/net/6lowpan/iphc.c +++ b/net/6lowpan/iphc.c @@ -745,6 +745,7 @@ int lowpan_header_decompress(struct sk_buff *skb, const struct net_device *dev, hdr.hop_limit, &hdr.daddr); skb_push(skb, sizeof(hdr)); + skb_reset_mac_header(skb); skb_reset_network_header(skb); skb_copy_to_linear_data(skb, &hdr, sizeof(hdr)); -- 2.17.1
