tcp: tcp_get_info() should fetch socket fields once

tcp_get_info() can be called without holding socket lock, so any socket fields can change under us. Use READ_ONCE() to fetch sk_pacing_rate and sk_max_pacing_rate Fixes: 977cb0e ("tcp: add pacing_rate information into tcp_info") Signed-off-by: Eric Dumazet <[email protected]> Signed-off-by: David S. Miller <[email protected]>
needcaffeine · Apr 17, 2015 · fad9dfe · fad9dfe
1 parent c3ffe6d
commit fad9dfe
Showing 1 changed file with 6 additions and 4 deletions.
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
@@ -2595,6 +2595,7 @@ void tcp_get_info(const struct sock *sk, struct tcp_info *info)
 	const struct tcp_sock *tp = tcp_sk(sk);
 	const struct inet_connection_sock *icsk = inet_csk(sk);
 	u32 now = tcp_time_stamp;
+	u32 rate;
 
 	memset(info, 0, sizeof(*info));
 
@@ -2655,10 +2656,11 @@ void tcp_get_info(const struct sock *sk, struct tcp_info *info)
 
 	info->tcpi_total_retrans = tp->total_retrans;
 
-	info->tcpi_pacing_rate = sk->sk_pacing_rate != ~0U ?
-					sk->sk_pacing_rate : ~0ULL;
-	info->tcpi_max_pacing_rate = sk->sk_max_pacing_rate != ~0U ?
-					sk->sk_max_pacing_rate : ~0ULL;
+	rate = READ_ONCE(sk->sk_pacing_rate);
+	info->tcpi_pacing_rate = rate != ~0U ? rate : ~0ULL;
+
+	rate = READ_ONCE(sk->sk_max_pacing_rate);
+	info->tcpi_max_pacing_rate = rate != ~0U ? rate : ~0ULL;
 }
 EXPORT_SYMBOL_GPL(tcp_get_info);