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net/packet: annotate data race in packet_sendmsg()

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[ 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@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Eric Dumazet 2021-06-10 09:00:12 -07:00 committed by Sasha Levin
parent 9707960ecf
commit f57132a887
1 changed files with 6 additions and 3 deletions
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9
net/packet/af_packet.c
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@ -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);
}
/*