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@redhat.com>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index c0d4a65931de5619c513b042e2dfc5f5eebe0aa0..88c3b5cf8d94c8a3afb4f154eb88511beff2086f 100644 (file)
--- 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);