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app_mixmonitor: cleanup datastore when monitor thread fails to launch 

launch_monitor_thread is responsible for creating and initializing
the mixmonitor, and dependent data structures. There was one off
nominal path after the datastore gets created that triggers when
the channel being monitored is hung up prior to monitor starting
itself.

If this happened the monitor thread would not "launch", and the
mixmonitor object and associated objects are freed, including the
underlying datastore data object. However, the datastore itself was
not removed from the channel, so when the channel eventually gets
destroyed it tries to access the previously freed datastore data
and crashes.

This patch removes and frees datastore object itself from the channel
before freeing the mixmonitor object thus ensuring the channel does
not call it when destroyed.

ASTERISK-28947 #close

Change-Id: Id4f9e958956d62473ed5ff06c98ae3436e839ff8
This commit is contained in:
Kevin Harwell 2020-12-23 13:06:19 -06:00 committed by George Joseph
parent 9ff548f1db
commit 0e1ba9a778
1 changed files with 22 additions and 1 deletions
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23
apps/app_mixmonitor.c
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@ -865,6 +865,24 @@ static int setup_mixmonitor_ds(struct mixmonitor *mixmonitor, struct ast_channel
return 0;
}
static void mixmonitor_ds_remove_and_free(struct ast_channel *chan, const char *datastore_id)
{
struct ast_datastore *datastore;
ast_channel_lock(chan);
datastore = ast_channel_datastore_find(chan, &mixmonitor_ds_info, datastore_id);
/*
* Currently the one place this function is called from guarantees a
* datastore is present, thus return checks can be avoided here.
*/
ast_channel_datastore_remove(chan, datastore);
ast_datastore_free(datastore);
ast_channel_unlock(chan);
}
static int launch_monitor_thread(struct ast_channel *chan, const char *filename,
unsigned int flags, int readvol, int writevol,
const char *post_process, const char *filename_write,
@ -940,7 +958,6 @@ static int launch_monitor_thread(struct ast_channel *chan, const char *filename,
pbx_builtin_setvar_helper(chan, uid_channel_var, datastore_id);
}
}
ast_free(datastore_id);
mixmonitor->name = ast_strdup(ast_channel_name(chan));
@ -990,12 +1007,16 @@ static int launch_monitor_thread(struct ast_channel *chan, const char *filename,
if (startmon(chan, &mixmonitor->audiohook)) {
ast_log(LOG_WARNING, "Unable to add '%s' spy to channel '%s'\n",
mixmonitor_spy_type, ast_channel_name(chan));
mixmonitor_ds_remove_and_free(chan, datastore_id);
ast_free(datastore_id);
ast_autochan_destroy(mixmonitor->autochan);
ast_audiohook_destroy(&mixmonitor->audiohook);
mixmonitor_free(mixmonitor);
return -1;
}
ast_free(datastore_id);
/* reference be released at mixmonitor destruction */
mixmonitor->callid = ast_read_threadstorage_callid();