From: Yun Lu Date: Fri, 11 Jul 2025 09:32:59 +0000 (+0800) Subject: af_packet: fix the SO_SNDTIMEO constraint not effective on tpacked_snd() X-Git-Tag: v6.16-rc7~37^2~30^2~1 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=c1ba3c0cbdb5e53a8ec5d708e99cd4c497028a13;p=thirdparty%2Fkernel%2Flinux.git af_packet: fix the SO_SNDTIMEO constraint not effective on tpacked_snd() Due to the changes in commit 581073f626e3 ("af_packet: do not call packet_read_pending() from tpacket_destruct_skb()"), every time tpacket_destruct_skb() is executed, the skb_completion is marked as completed. When wait_for_completion_interruptible_timeout() returns completed, the pending_refcnt has not yet been reduced to zero. Therefore, when ph is NULL, the wait function may need to be called multiple times until packet_read_pending() finally returns zero. We should call sock_sndtimeo() only once, otherwise the SO_SNDTIMEO constraint could be way off. Fixes: 581073f626e3 ("af_packet: do not call packet_read_pending() from tpacket_destruct_skb()") Cc: stable@kernel.org Suggested-by: Eric Dumazet Signed-off-by: Yun Lu Reviewed-by: Eric Dumazet Reviewed-by: Willem de Bruijn Signed-off-by: David S. Miller --- diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 3d43f3eae7599..7089b8c2a655f 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2785,7 +2785,7 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg) int len_sum = 0; int status = TP_STATUS_AVAILABLE; int hlen, tlen, copylen = 0; - long timeo = 0; + long timeo; mutex_lock(&po->pg_vec_lock); @@ -2839,6 +2839,7 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg) if ((size_max > dev->mtu + reserve + VLAN_HLEN) && !vnet_hdr_sz) size_max = dev->mtu + reserve + VLAN_HLEN; + timeo = sock_sndtimeo(&po->sk, msg->msg_flags & MSG_DONTWAIT); reinit_completion(&po->skb_completion); do { @@ -2846,7 +2847,6 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg) TP_STATUS_SEND_REQUEST); if (unlikely(ph == NULL)) { if (need_wait && skb) { - timeo = sock_sndtimeo(&po->sk, msg->msg_flags & MSG_DONTWAIT); timeo = wait_for_completion_interruptible_timeout(&po->skb_completion, timeo); if (timeo <= 0) { err = !timeo ? -ETIMEDOUT : -ERESTARTSYS;