From: Eric Dumazet Date: Wed, 3 Jun 2026 07:29:55 +0000 (+0000) Subject: ieee802154: 6lowpan: only accept IPv6 packets in lowpan_xmit() X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3a5f3f7aff18bcc36a57839cf50cf0cc8de707f3;p=thirdparty%2Fkernel%2Flinux.git ieee802154: 6lowpan: only accept IPv6 packets in lowpan_xmit() The aoe driver (or similar) generates a non-IPv6 packet (e.g., ETH_P_AOE) and queues it for transmission via dev_queue_xmit() on a 6LoWPAN interface (configured by the user or test case). Since the packet is not IPv6, the 6LoWPAN header_ops->create function (lowpan_header_create or header_create) returns early without initializing the lowpan_addr_info structure in the skb headroom. In the transmit function (lowpan_xmit), the driver calls lowpan_header (or setup_header) which unconditionally copies and uses the lowpan_addr_info from the headroom, which contains uninitialized data. Fix this by dropping non IPv6 packets. A similar fix is needed in net/bluetooth/6lowpan.c bt_xmit(). Fixes: 4dc315e267fe ("ieee802154: 6lowpan: move transmit functionality") Reported-by: syzbot+f13c19f75e1097abd116@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/6a1fd763.278b5b03.2bcf39.0049.GAE@google.com/T/#u Signed-off-by: Eric Dumazet Reviewed-by: Miquel Raynal Link: https://patch.msgid.link/20260603072955.4032221-1-edumazet@google.com Signed-off-by: Jakub Kicinski --- diff --git a/net/ieee802154/6lowpan/tx.c b/net/ieee802154/6lowpan/tx.c index 0c07662b44c0..4df76ff50699 100644 --- a/net/ieee802154/6lowpan/tx.c +++ b/net/ieee802154/6lowpan/tx.c @@ -255,6 +255,11 @@ netdev_tx_t lowpan_xmit(struct sk_buff *skb, struct net_device *ldev) pr_debug("package xmit\n"); + if (skb->protocol != htons(ETH_P_IPV6)) { + kfree_skb(skb); + return NET_XMIT_DROP; + } + WARN_ON_ONCE(skb->len > IPV6_MIN_MTU); /* We must take a copy of the skb before we modify/replace the ipv6