From 533fe36957e2fc78e2c76fb1a91f5b17c3dfb85e Mon Sep 17 00:00:00 2001 From: Mike Perry Date: Tue, 26 Jul 2022 22:28:02 +0000 Subject: [PATCH] Add an underflow check to a cwnd error condition. --- src/core/or/congestion_control_common.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/src/core/or/congestion_control_common.c b/src/core/or/congestion_control_common.c index 71cd666ee2..42f816690f 100644 --- a/src/core/or/congestion_control_common.c +++ b/src/core/or/congestion_control_common.c @@ -882,10 +882,19 @@ congestion_control_update_circuit_bdp(congestion_control_t *cc, if (!cc->ewma_rtt_usec) { uint64_t cwnd = cc->cwnd; + tor_assert_nonfatal(cc->cwnd <= cwnd_max); + /* If the channel is blocked, keep subtracting off the chan_q * until we hit the min cwnd. */ if (blocked_on_chan) { - cwnd = MAX(cwnd - chan_q, cc->cwnd_min); + /* Cast is fine because we're less than int32 */ + if (chan_q >= (int64_t)cwnd) { + log_notice(LD_CIRC, + "Clock stall with large chanq: %d %"PRIu64, chan_q, cwnd); + cwnd = cc->cwnd_min; + } else { + cwnd = MAX(cwnd - chan_q, cc->cwnd_min); + } cc->blocked_chan = 1; } else { cc->blocked_chan = 0;