This is a note to let you know that I've just added the patch titled net/packet: fix packet_sock xmit return value checking to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: net-packet-fix-packet_sock-xmit-return-value-checkin.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit c3e6018392c1735161c042c7b31293777fa59f85 Author: Hangbin Liu <liuhangbin@xxxxxxxxx> Date: Thu Apr 14 16:49:25 2022 +0800 net/packet: fix packet_sock xmit return value checking [ Upstream commit 29e8e659f984be00d75ec5fef4e37c88def72712 ] packet_sock xmit could be dev_queue_xmit, which also returns negative errors. So only checking positive errors is not enough, or userspace sendmsg may return success while packet is not send out. Move the net_xmit_errno() assignment in the braces as checkpatch.pl said do not use assignment in if condition. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Flavio Leitner <fbl@xxxxxxxxxx> Signed-off-by: Hangbin Liu <liuhangbin@xxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index c0d4a65931de..88c3b5cf8d94 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2820,8 +2820,9 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg) status = TP_STATUS_SEND_REQUEST; err = po->xmit(skb); - if (unlikely(err > 0)) { - err = net_xmit_errno(err); + if (unlikely(err != 0)) { + if (err > 0) + err = net_xmit_errno(err); if (err && __packet_get_status(po, ph) == TP_STATUS_AVAILABLE) { /* skb was destructed already */ @@ -3022,8 +3023,12 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len) skb->no_fcs = 1; err = po->xmit(skb); - if (err > 0 && (err = net_xmit_errno(err)) != 0) - goto out_unlock; + if (unlikely(err != 0)) { + if (err > 0) + err = net_xmit_errno(err); + if (err) + goto out_unlock; + } dev_put(dev);