From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ Upstream commit 6ffc57ea004234d9373c57b204fd10370a69f392 ]
A recent patch added READ_ONCE() in packet_bind() and packet_bind_spkt()
This is better handled by reading pkt_sk(sk)->num later
in packet_do_bind() while appropriate lock is held.
READ_ONCE() in writers are often an evidence of something being wrong.
Fixes: 822b5a1c17df ("af_packet: Fix data-races of pkt_sk(sk)->num.")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reviewed-by: Willem de Bruijn <willemb@xxxxxxxxxx>
Reviewed-by: Jiri Pirko <jiri@xxxxxxxxxx>
Reviewed-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230526154342.2533026-1-edumazet@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/packet/af_packet.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index f3513316743ad..b79d2fa788061 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -3193,6 +3193,9 @@ static int packet_do_bind(struct sock *sk, const char *name, int ifindex,
lock_sock(sk);
spin_lock(&po->bind_lock);
+ if (!proto)
+ proto = po->num;
+
rcu_read_lock();
if (po->fanout) {
@@ -3291,7 +3294,7 @@ static int packet_bind_spkt(struct socket *sock, struct sockaddr *uaddr,
memcpy(name, uaddr->sa_data, sizeof(uaddr->sa_data_min));
name[sizeof(uaddr->sa_data_min)] = 0;
- return packet_do_bind(sk, name, 0, READ_ONCE(pkt_sk(sk)->num));
+ return packet_do_bind(sk, name, 0, 0);
}
static int packet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
@@ -3308,8 +3311,7 @@ static int packet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len
if (sll->sll_family != AF_PACKET)
return -EINVAL;
- return packet_do_bind(sk, NULL, sll->sll_ifindex,
- sll->sll_protocol ? : READ_ONCE(pkt_sk(sk)->num));
+ return packet_do_bind(sk, NULL, sll->sll_ifindex, sll->sll_protocol);
}
static struct proto packet_proto = {
--
2.39.2
