[PATCH 5.10 18/65] tcp: Fix data-races around sysctl_tcp_moderate_rcvbuf.

Greg Kroah-Hartman
2022-08-01T11:53:23Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

commit 780476488844e070580bfc9e3bc7832ec1cea883 upstream.

While reading sysctl_tcp_moderate_rcvbuf, it can be changed
concurrently. Thus, we need to add READ_ONCE() to its readers.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv4/tcp_input.c | 2 +-
net/mptcp/protocol.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -693,7 +693,7 @@ void tcp_rcv_space_adjust(struct sock *s
* <prev RTT . ><current RTT .. ><next RTT .... >
*/

- if (sock_net(sk)->ipv4.sysctl_tcp_moderate_rcvbuf &&
+ if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_moderate_rcvbuf) &&
!(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) {
int rcvmem, rcvbuf;
u64 rcvwin, grow;
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1421,7 +1421,7 @@ static void mptcp_rcv_space_adjust(struc
if (msk->rcvq_space.copied <= msk->rcvq_space.space)
goto new_measure;

- if (sock_net(sk)->ipv4.sysctl_tcp_moderate_rcvbuf &&
+ if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_moderate_rcvbuf) &&
!(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) {
int rcvmem, rcvbuf;
u64 rcvwin, grow;