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daemon: Protect against double free of callback state while shutting down

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When CTDB is shut down and monitoring has been stopped, monitor_context
gets freed and all the callback states hanging off it.  This includes
callback state for current_monitor, if the current monitor event has
not yet finished.  As a result, when the shutdown event is called,
current_monitor->callback state is not NULL, but it's actually freed
and it's a dangling reference.

So before executing callback function and freeing callback state check
if ctdb->monitor->monitor_context is not NULL.

Signed-off-by: Amitay Isaacs <amitay@gmail.com>

(This used to be ctdb commit 7d8546ee4353851f0543d0ca2c4c67cb0cc75aea)
This commit is contained in:
Amitay Isaacs 2012-10-29 14:56:10 +11:00
parent 30299c387f
commit 4a6fa39ff9
3 changed files with 11 additions and 2 deletions
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1
ctdb/include/ctdb_private.h
View File

@ -1343,6 +1343,7 @@ int ctdb_repack(struct ctdb_context *ctdb, int argc, const char **argv);
void ctdb_block_signal(int signum);
void ctdb_unblock_signal(int signum);
int32_t ctdb_monitoring_mode(struct ctdb_context *ctdb);
bool ctdb_stopped_monitoring(struct ctdb_context *ctdb);
int ctdb_set_child_logging(struct ctdb_context *ctdb);
void ctdb_lockdown_memory(struct ctdb_context *ctdb);

7
ctdb/server/ctdb_monitor.c
View File

@ -506,3 +506,10 @@ int32_t ctdb_monitoring_mode(struct ctdb_context *ctdb)
return ctdb->monitor->monitoring_mode;
}
/*
* Check if monitoring has been stopped
*/
bool ctdb_stopped_monitoring(struct ctdb_context *ctdb)
{
return (ctdb->monitor->monitor_context == NULL ? true : false);
}

5
ctdb/server/eventscript.c
View File

@ -781,8 +781,9 @@ static int ctdb_event_script_callback_v(struct ctdb_context *ctdb,
if (ctdb->current_monitor) {
struct ctdb_event_script_state *ms = talloc_get_type(ctdb->current_monitor, struct ctdb_event_script_state);
/* cancel it */
if (ms->callback != NULL) {
/* Cancel current monitor callback state only if monitoring
* context ctdb->monitor->monitor_context has not been freed */
if (ms->callback != NULL && !ctdb_stopped_monitoring(ctdb)) {
ms->callback->fn(ctdb, -ECANCELED, ms->callback->private_data);
talloc_free(ms->callback);
}