From: Eric Dumazet edumazet@google.com
[ 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@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 Signed-off-by: Sasha Levin sashal@kernel.org --- 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 = {