[PATCH net-next] tcp: warn on negative reordering values

[Soheil Hassas Yeganeh <soheil.kdev@gmail.com>]

From: Soheil Hassas Yeganeh <soheil@google.com>

Commit bafbb9c73241 ("tcp: eliminate negative reordering
in tcp_clean_rtx_queue") fixes an issue for negative
reordering metrics.

To be resilient to such errors, warn and return
when a negative metric is passed to tcp_update_reordering().

Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/ipv4/tcp_input.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index f27dff64e59e..eb5eb87060a2 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -886,6 +886,9 @@ static void tcp_update_reordering(struct sock *sk, const int metric,
 	struct tcp_sock *tp = tcp_sk(sk);
 	int mib_idx;
 
+	if (WARN_ON_ONCE(metric < 0))
+		return;
+
 	if (metric > tp->reordering) {
 		tp->reordering = min(sysctl_tcp_max_reordering, metric);
 
-- 
2.13.0.303.g4ebf302169-goog