Patch "net/packet: fix packet_sock xmit return value checking" has been added to the 5.17-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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 5.17-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-5.17 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit cf0e778b5aaa66ad3cf3598cf7812eac69206a02
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 a7273af2d900..e3c60251e708 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2856,8 +2856,9 @@ 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 */
@@ -3058,8 +3059,12 @@ 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);