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ENT-14927: Fixed cf-serverd crash when policy reload races with a new connection #6464

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Merged
olehermanse merged 1 commit into from
Nov 10, 2026
Merged

ENT-14927: Fixed cf-serverd crash when policy reload races with a new connection #6464

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30 changes: 24 additions & 6 deletions cf-serverd/cf-serverd-functions.c
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Original file line number Diff line number Diff line change
Expand Up @@ -374,7 +374,7 @@ static void DeleteAuthList(Auth **list, Auth **list_tail)
*list_tail = NULL;
}

/* Must not be called unless ACTIVE_THREADS is zero: */
/* Must not be called unless ConnectionsInFlight() is zero: */
static void ClearAuthAndACLs(void)
{
/* Must have no currently open connections to free the ACLs. */
Expand Down Expand Up @@ -674,6 +674,24 @@ static void GracefulStop()
}
#endif // HAVE_SYSTEMD_SD_DAEMON_H

/* Number of connections still being handled.
*
* A connection is added to SERVER_ACCESS.connectionlist before its handler
* thread increments ACTIVE_THREADS, and removed only after the thread has
* decremented it again, so ACTIVE_THREADS alone can be zero while a
* connection is still in flight.
*
* Must be called with cft_server_children locked.
*/
static int ConnectionsInFlight(void)
{
ThreadLock(cft_count);
const int listed = (int) ListLen(SERVER_ACCESS.connectionlist);
ThreadUnlock(cft_count);

return MAX(ACTIVE_THREADS, listed);
}

/* Wait for connection-handler threads to finish their work.
*
* @return Number of live threads remaining after waiting.
Expand All @@ -684,7 +702,7 @@ static int WaitOnThreads(int graceful_time)
for (int i = graceful_time; i > 0; i--)
{
ThreadLock(cft_server_children);
result = ACTIVE_THREADS;
result = ConnectionsInFlight();
ThreadUnlock(cft_server_children);

if (result == 0)
Expand Down Expand Up @@ -749,15 +767,15 @@ static void CollectCallIfDue(EvalContext *ctx)

/* Check for new policy just before spawning a thread.
*
* Server reconfiguration can only happen when no threads are active,
* so this is a good time to do it; but we do still have to check for
* running threads. */
* Server reconfiguration can only happen when no connections are being
* handled, so this is a good time to do it; but we do still have to check
* for connections in flight. */
static void PolicyUpdateIfSafe(EvalContext *ctx, Policy **policy,
GenericAgentConfig *config)
{
ThreadLock(cft_server_children);
int prior = COLLECT_INTERVAL;
if (ACTIVE_THREADS == 0)
if (ConnectionsInFlight() == 0)
{
CheckFileChanges(ctx, policy, config);
}
Expand Down
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