aboutsummaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorNeels Hofmeyr <neels@hofmeyr.de>2019-01-28 19:06:53 +0100
committerNeels Hofmeyr <neels@hofmeyr.de>2019-01-31 17:40:24 +0100
commit89991fdb7c01fa42e323577b4026985e580763cf (patch)
treeb91957962a41177a61365a1719a6eddcd0b5593b
parentbd5a1dc84f0124d99a89ac187f15c7d34beea210 (diff)
osmo_fsm_inst_state_chg(): clamp timeout_secs to <= ~68 years
During testing of the upcoming tdef API, it became apparent that passing very large timeout values to osmo_fsm_inst_state_chg() wraps back in the number range, and might actually result in effectively very short timeouts instead. Since time_t's range is not well defined across platforms, use a reasonable maximum value of signed 32 bit integer. Hence this will be safe at least on systems with an int32_t for struct timeval.tv_sec and larger. Clamp the osmo_fsm_inst_state_chg() timeout_secs argument to a maximum of 0x7fffffff, which amounts to just above 68 years: float(0x7fffffff) / (60. * 60 * 24 * 365.25) = 68.04965038532715 (In upcoming patch Ibd6b1ed7f1bd6e1f2e0fde53352055a4468f23e5, this can be verified to work by invoking tdef_test manually with a cmdline argument passed to enable the range check.) Change-Id: I35ec4654467b1d6040c8aa215049766089e5e64a
-rw-r--r--src/fsm.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/src/fsm.c b/src/fsm.c
index ae7c0f5..0d31f87 100644
--- a/src/fsm.c
+++ b/src/fsm.c
@@ -437,6 +437,11 @@ static int state_chg(struct osmo_fsm_inst *fi, uint32_t new_state,
uint32_t old_state = fi->state;
const struct osmo_fsm_state *st = &fsm->states[fi->state];
+ /* Limit to 0x7fffffff seconds as explained by
+ * _osmo_fsm_inst_state_chg()'s API doc. */
+ if (timeout_secs > 0x7fffffff)
+ timeout_secs = 0x7fffffff;
+
/* validate if new_state is a valid state */
if (!(st->out_state_mask & (1 << new_state))) {
LOGPFSMLSRC(fi, LOGL_ERROR, file, line,
@@ -493,9 +498,16 @@ static int state_chg(struct osmo_fsm_inst *fi, uint32_t new_state,
* timer_cb. If passing timeout_secs == 0, it is recommended to also pass T ==
* 0, so that fi->T is reset to 0 when no timeout is invoked.
*
+ * Range: since time_t's maximum value is not well defined in a cross platform
+ * way, clamp timeout_secs to the maximum of the signed 32bit range, or roughly
+ * 68 years (float(0x7fffffff) / (60. * 60 * 24 * 365.25) = 68.0497). Thus
+ * ensure that very large timeouts do not wrap around to become very small
+ * ones. Note though that this might still be unsafe on systems with a time_t
+ * range below 32 bits.
+ *
* \param[in] fi FSM instance whose state is to change
* \param[in] new_state The new state into which we should change
- * \param[in] timeout_secs Timeout in seconds (if !=0)
+ * \param[in] timeout_secs Timeout in seconds (if !=0), maximum-clamped to 2147483647 seconds.
* \param[in] T Timer number (if \ref timeout_secs != 0)
* \param[in] file Calling source file (from osmo_fsm_inst_state_chg macro)
* \param[in] line Calling source line (from osmo_fsm_inst_state_chg macro)