This is a note to let you know that I've just added the patch titled
af_packet: do not use READ_ONCE() in packet_bind()
to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
af_packet-do-not-use-read_once-in-packet_bind.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit bc5c405171e99fd9b926b2a2928188f786caaea2
Author: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Fri May 26 15:43:42 2023 +0000
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: 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>
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 131c347bba56b..228a409eb92da 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -3153,6 +3153,9 @@ 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) {
@@ -3255,7 +3258,7 @@ static int packet_bind_spkt(struct socket *sock, struct sockaddr *uaddr,
memcpy(name, uaddr->sa_data, sizeof(uaddr->sa_data));
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)
@@ -3272,8 +3275,7 @@ 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 = {
