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Commit 26e83085 authored by Eric Dumazet's avatar Eric Dumazet Committed by Greg Kroah-Hartman
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af_packet: do not use READ_ONCE() in packet_bind() 



[ 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: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarWillem de Bruijn <willemb@google.com>
Reviewed-by: default avatarJiri Pirko <jiri@nvidia.com>
Reviewed-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20230526154342.2533026-1-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 43f1402d

net/packet/af_packet.c

+5 −3
Original line number Original line Diff line number Diff line
@@ -3128,6 +3128,9 @@ static int packet_do_bind(struct sock *sk, const char *name, int ifindex, 




	lock_sock(sk);

	lock_sock(sk);

	spin_lock(&po->bind_lock);

	spin_lock(&po->bind_lock);

	if (!proto)

		proto = po->num;



	rcu_read_lock();

	rcu_read_lock();





	if (po->fanout) {

	if (po->fanout) {
@@ -3230,7 +3233,7 @@ static int packet_bind_spkt(struct socket *sock, struct sockaddr *uaddr, 
	memcpy(name, uaddr->sa_data, sizeof(uaddr->sa_data));

	memcpy(name, uaddr->sa_data, sizeof(uaddr->sa_data));

	name[sizeof(uaddr->sa_data)] = 0;

	name[sizeof(uaddr->sa_data)] = 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)

static int packet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
@@ -3247,8 +3250,7 @@ static int packet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len 
	if (sll->sll_family != AF_PACKET)

	if (sll->sll_family != AF_PACKET)

		return -EINVAL;

		return -EINVAL;





	return packet_do_bind(sk, NULL, sll->sll_ifindex,

	return packet_do_bind(sk, NULL, sll->sll_ifindex, sll->sll_protocol);

			      sll->sll_protocol ? : READ_ONCE(pkt_sk(sk)->num));

}

}





static struct proto packet_proto = {

static struct proto packet_proto = {