From: Selva Nair <selva.n...@gmail.com>
Time interval arithmetic can overflow especially when user
defined intervals are involved. E.g., see Trac #922.
Avoid this by reordering the arithmetic operation in
event_timeout_trigger(). Also avoid unnecessary casting of time
variable to int.
Time until wakeup is now calculated like:
time_t wakeup = (last - now) + delay
Here delay is of type int, but is +ve by construction. Time backtrack
protection in OpenVPN ensures (last - now) <= 0. Then the above
expression cannot overflow (provided time_t is at least as large
as int).
A similar expression in interval.h is also changed.
(This patch grew out of patch 168 by Steffan Karger.)
Signed-off-by: Selva Nair <selva.n...@gmail.com>
---
src/openvpn/interval.c | 8 +++++---
src/openvpn/interval.h | 2 +-
2 files changed, 6 insertions(+), 4 deletions(-)
diff --git a/src/openvpn/interval.c b/src/openvpn/interval.c
index 00ee627..b728560 100644
--- a/src/openvpn/interval.c
+++ b/src/openvpn/interval.c
@@ -51,11 +51,12 @@ event_timeout_trigger(struct event_timeout *et,
if (et->defined)
{
- int wakeup = (int) et->last + et->n - local_now;
+ time_t wakeup = et->last - local_now + et->n;
if (wakeup <= 0)
{
#if INTERVAL_DEBUG
- dmsg(D_INTERVAL, "EVENT event_timeout_trigger (%d) etcr=%d",
et->n, et_const_retry);
+ dmsg(D_INTERVAL, "EVENT event_timeout_trigger (%d) etcr=%d", et->n,
+ et_const_retry);
#endif
if (et_const_retry < 0)
{
@@ -72,7 +73,8 @@ event_timeout_trigger(struct event_timeout *et,
if (tv && wakeup < tv->tv_sec)
{
#if INTERVAL_DEBUG
- dmsg(D_INTERVAL, "EVENT event_timeout_wakeup (%d/%d) etcr=%d",
wakeup, et->n, et_const_retry);
+ dmsg(D_INTERVAL, "EVENT event_timeout_wakeup (%d/%d) etcr=%d",
+ (int) wakeup, et->n, et_const_retry);
#endif
tv->tv_sec = wakeup;
tv->tv_usec = 0;
diff --git a/src/openvpn/interval.h b/src/openvpn/interval.h
index 826a08b..5623f3a 100644
--- a/src/openvpn/interval.h
+++ b/src/openvpn/interval.h
@@ -196,7 +196,7 @@ event_timeout_modify_wakeup(struct event_timeout *et,
interval_t n)
static inline interval_t
event_timeout_remaining(struct event_timeout *et)
{
- return (int) et->last + et->n - now;
+ return (interval_t) (et->last - now + et->n);
}
/*
--
2.1.4
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