[PATCH 4.19 14/53] net/packet: fix packet_sock xmit return value checking

Greg Kroah-Hartman
2022-04-26T08:33:35Z

From: Hangbin Liu <liuhangbin@gmail.com>

[ 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>
---
net/packet/af_packet.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index b951f411dded..f654f79e3310 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2791,8 +2791,9 @@ 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 */
@@ -2993,8 +2994,12 @@ 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);

--
2.35.1