tcp: annotate data-races around icsk->icsk_syn_retries

do_tcp_getsockopt() and reqsk_timer_handler() read
icsk->icsk_syn_retries while another cpu might change its value.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20230719212857.3943972-7-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 0cc19cf..aeebe88 100644 (file)
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -1019,7 +1019,7 @@ static void reqsk_timer_handler(struct timer_list *t)
 
        icsk = inet_csk(sk_listener);
        net = sock_net(sk_listener);
-       max_syn_ack_retries = icsk->icsk_syn_retries ? :
+       max_syn_ack_retries = READ_ONCE(icsk->icsk_syn_retries) ? :
                READ_ONCE(net->ipv4.sysctl_tcp_synack_retries);
        /* Normally all the openreqs are young and become mature
         * (i.e. converted to established socket) for first timeout.

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 574fd0d..9f74ac1 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3291,7 +3291,7 @@ int tcp_sock_set_syncnt(struct sock *sk, int val)
                return -EINVAL;
 
        lock_sock(sk);
-       inet_csk(sk)->icsk_syn_retries = val;
+       WRITE_ONCE(inet_csk(sk)->icsk_syn_retries, val);
        release_sock(sk);
        return 0;
 }
@@ -3572,7 +3572,7 @@ int do_tcp_setsockopt(struct sock *sk, int level, int optname,
                if (val < 1 || val > MAX_TCP_SYNCNT)
                        err = -EINVAL;
                else
-                       icsk->icsk_syn_retries = val;
+                       WRITE_ONCE(icsk->icsk_syn_retries, val);
                break;
 
        case TCP_SAVE_SYN:
@@ -3993,7 +3993,7 @@ int do_tcp_getsockopt(struct sock *sk, int level,
                val = keepalive_probes(tp);
                break;
        case TCP_SYNCNT:
-               val = icsk->icsk_syn_retries ? :
+               val = READ_ONCE(icsk->icsk_syn_retries) ? :
                        READ_ONCE(net->ipv4.sysctl_tcp_syn_retries);
                break;
        case TCP_LINGER2: