[PATCH 6.1 036/127] net: annotate data-race around sk->sk_txrehash

Greg Kroah-Hartman
2023-08-09T10:53:41Z

From: Eric Dumazet <edumazet@google.com>

[ 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 <edumazet@google.com>
Cc: Akhmat Karakotov <hmukos@yandex-team.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 9483820833c5b..77abd69c56dde 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1521,7 +1521,9 @@ int sk_setsockopt(struct sock *sk, int level, int optname,
}
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:
--
2.40.1