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af_packet: do not use READ_ONCE() in packet_bind()

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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: 822b5a1c17 ("af_packet: Fix data-races of pkt_sk(sk)->num.")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20230526154342.2533026-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2023-05-26 15:43:42 +00:00 committed by Jakub Kicinski
parent 0684f29a89
commit 6ffc57ea00
1 changed files with 5 additions and 3 deletions
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8
net/packet/af_packet.c
View file

@ -3201,6 +3201,9 @@ 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) {
@ -3299,7 +3302,7 @@ 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)
@ -3316,8 +3319,7 @@ 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 = {