From 44aa1e461ccd1c2e49cffad5e75e1b944ec590ef Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 28 May 2024 12:52:53 +0000 Subject: [PATCH] tcp: fix races in tcp_v[46]_err() [ Upstream commit fde6f897f2a184546bf5516ac736523ef24dc6a7 ] These functions have races when they: 1) Write sk->sk_err 2) call sk_error_report(sk) 3) call tcp_done(sk) As described in prior patches in this series: An smp_wmb() is missing. We should call tcp_done() before sk_error_report(sk) to have consistent tcp_poll() results on SMP hosts. Use tcp_done_with_error() where we centralized the correct sequence. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Dumazet Acked-by: Neal Cardwell Link: https://lore.kernel.org/r/20240528125253.1966136-5-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/ipv4/tcp_ipv4.c | 11 +++-------- net/ipv6/tcp_ipv6.c | 10 +++------- 2 files changed, 6 insertions(+), 15 deletions(-) diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 7c2ca4df0daa..48ec2c1777d4 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -602,15 +602,10 @@ int tcp_v4_err(struct sk_buff *skb, u32 info) ip_icmp_error(sk, skb, err, th->dest, info, (u8 *)th); - if (!sock_owned_by_user(sk)) { - WRITE_ONCE(sk->sk_err, err); - - sk_error_report(sk); - - tcp_done(sk); - } else { + if (!sock_owned_by_user(sk)) + tcp_done_with_error(sk, err); + else WRITE_ONCE(sk->sk_err_soft, err); - } goto out; } diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 07bcb690932e..d0034916d386 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -488,14 +488,10 @@ static int tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, ipv6_icmp_error(sk, skb, err, th->dest, ntohl(info), (u8 *)th); - if (!sock_owned_by_user(sk)) { - WRITE_ONCE(sk->sk_err, err); - sk_error_report(sk); /* Wake people up to see the error (see connect in sock.c) */ - - tcp_done(sk); - } else { + if (!sock_owned_by_user(sk)) + tcp_done_with_error(sk, err); + else WRITE_ONCE(sk->sk_err_soft, err); - } goto out; case TCP_LISTEN: break;