From: Soheil Hassas Yeganeh <soh...@google.com>
tcp_ack() can call tcp_fragment() which may dededuct the
value tp->fackets_out when MSS changes. When prior_fackets
is larger than tp->fackets_out, tcp_clean_rtx_queue() can
invoke tcp_update_reordering() with negative values. This
results in absurd tp->reodering values higher than
sysctl_tcp_max_reordering.
Note that tcp_update_reordering indeeds sets tp->reordering
to min(sysctl_tcp_max_reordering, metric), but because
the comparison is signed, a negative metric always wins.
Fixes: c7caf8d3ed7a ("[TCP]: Fix reord detection due to snd_una covered holes")
Reported-by: Rebecca Isaacs <risa...@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soh...@google.com>
Signed-off-by: Neal Cardwell <ncardw...@google.com>
Signed-off-by: Yuchung Cheng <ych...@google.com>
Signed-off-by: Eric Dumazet <eduma...@google.com>
---
net/ipv4/tcp_input.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 9739962bfb3f..f27dff64e59e 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3190,7 +3190,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, int
prior_fackets,
int delta;
/* Non-retransmitted hole got filled? That's reordering
*/
- if (reord < prior_fackets)
+ if (reord < prior_fackets && reord <= tp->fackets_out)
tcp_update_reordering(sk, tp->fackets_out -
reord, 0);
delta = tcp_is_fack(tp) ? pkts_acked :
--
2.13.0.rc2.291.g57267f2277-goog
