From 0317c8322d9ac86a2bf251f94efc7fe96643e0fb Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 28 Jul 2023 15:03:09 +0000 Subject: [PATCH] net: annotate data-race around sk->sk_txrehash [ Upstream commit c76a0328899bbe226f8adeb88b8da9e4167bd316 ] sk_getsockopt() runs locklessly. This means sk->sk_txrehash can be read while other threads are changing its value. Other locations were handled in commit cb6cd2cec799 ("tcp: Change SYN ACK retransmit behaviour to account for rehash") Fixes: 26859240e4ee ("txhash: Add socket option to control TX hash rethink behavior") Signed-off-by: Eric Dumazet Cc: Akhmat Karakotov Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/core/sock.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/net/core/sock.c b/net/core/sock.c index 9483820833c5..77abd69c56dd 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -1521,7 +1521,9 @@ set_sndbuf: } if ((u8)val == SOCK_TXREHASH_DEFAULT) val = READ_ONCE(sock_net(sk)->core.sysctl_txrehash); - /* Paired with READ_ONCE() in tcp_rtx_synack() */ + /* Paired with READ_ONCE() in tcp_rtx_synack() + * and sk_getsockopt(). + */ WRITE_ONCE(sk->sk_txrehash, (u8)val); break; @@ -1927,7 +1929,8 @@ int sk_getsockopt(struct sock *sk, int level, int optname, break; case SO_TXREHASH: - v.val = sk->sk_txrehash; + /* Paired with WRITE_ONCE() in sk_setsockopt() */ + v.val = READ_ONCE(sk->sk_txrehash); break; default: