diff options
| author | Michael Tuexen <tuexen@FreeBSD.org> | 2026-07-28 20:15:22 +0000 |
|---|---|---|
| committer | Mark Johnston <markj@FreeBSD.org> | 2026-10-13 14:10:21 +0000 |
| commit | cf95af02eb153c39641d0f12650ff5752619d7d5 (patch) | |
| tree | c2d52f4468b64ee1b2ec15d9b97ee27ce9cb6fff | |
| parent | c8fe55b4726ae56ceaa6d0828403780dcef72c54 (diff) | |
tcp: improve handling of stopped timers
When a TCP timer is stopped, t_timers[] is set to SBT_MAX. Adding the
corresponding t_precisions[], if it is not zero, would result in
overflows in tcp_timer_next(). To avoid this, skip stopped timers.
The problem was identified while debugging uperf by Lukas Book and
an initial patch was provided by him. The committed patch was
suggested by glebius.
The problem can be observed by running netstat -nxptcp and looking for
negative timer values and by observing very long running timers in
some cases.
Approved by: so
Security: FreeBSD-EN-26:27.tcp
Reported by: Lukas Book <lkbook@outlook.de>
Reviewed by: glebius
Differential Revision: https://reviews.freebsd.org/D58484
(cherry picked from commit 52b7cbcb78c14e89f6faec8da5acc2caa3d37208)
(cherry picked from commit e8d1cee437414dd9bb3c779ff0a0c234fb7d411e)
| -rw-r--r-- | sys/netinet/tcp_timer.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/sys/netinet/tcp_timer.c b/sys/netinet/tcp_timer.c index 57c57666fa3a..56c50faaf4d1 100644 --- a/sys/netinet/tcp_timer.c +++ b/sys/netinet/tcp_timer.c @@ -859,6 +859,8 @@ tcp_timer_next(struct tcpcb *tp, sbintime_t *precision) sbintime_t after, before; for (i = 0, rv = TT_N, after = before = SBT_MAX; i < TT_N; i++) { + if (tp->t_timers[i] == SBT_MAX) + continue; if (tp->t_timers[i] < after) { after = tp->t_timers[i]; rv = i; |