diff options
| author | Michael Tuexen <tuexen@FreeBSD.org> | 2026-07-28 20:15:22 +0000 |
|---|---|---|
| committer | Mark Johnston <markj@FreeBSD.org> | 2026-10-13 13:47:11 +0000 |
| commit | 11f0c61eecb83c1b613347243c8aca5c0af2752c (patch) | |
| tree | 5d9349c01dd2f15e2c12bd79857ecea91e8748d6 | |
| parent | 1c821dc49b536cf2d925487324e0785a7a1400c6 (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 85485a570d4f9c5f9d9b867ee847b8ee5f7d2445)
| -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 1c687e94bb4a..5e01716e7a44 100644 --- a/sys/netinet/tcp_timer.c +++ b/sys/netinet/tcp_timer.c @@ -850,6 +850,8 @@ 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; |