From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ Upstream commit d1b5bee4c8be01585033be9b3a8878789285285f ]
There is a known race in packet_sendmsg(), addressed
in commit 32d3182cd2cd ("net/packet: fix race in tpacket_snd()")
Now we have data_race(), we can use it to avoid a future KCSAN warning,
as syzbot loves stressing af_packet sockets :)
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/packet/af_packet.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index ddb68aa836f7..7892d7074847 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -3033,10 +3033,13 @@ static int packet_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
struct sock *sk = sock->sk;
struct packet_sock *po = pkt_sk(sk);
- if (po->tx_ring.pg_vec)
+ /* Reading tx_ring.pg_vec without holding pg_vec_lock is racy.
+ * tpacket_snd() will redo the check safely.
+ */
+ if (data_race(po->tx_ring.pg_vec))
return tpacket_snd(po, msg);
- else
- return packet_snd(sock, msg, len);
+
+ return packet_snd(sock, msg, len);
}
/*
--
2.30.2
