From 6ffc57ea004234d9373c57b204fd10370a69f392 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 26 May 2023 15:43:42 +0000 Subject: af_packet: do not use READ_ONCE() in packet_bind() 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 Reviewed-by: Willem de Bruijn Reviewed-by: Jiri Pirko Reviewed-by: Kuniyuki Iwashima Link: https://lore.kernel.org/r/20230526154342.2533026-1-edumazet@google.com Signed-off-by: Jakub Kicinski --- net/packet/af_packet.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'net/packet') diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index a1f9a0e9f3c8..a2dbeb264f26 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -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 = { -- cgit