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app_dial.c: Moved channel lock to prevent deadlock

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It's reproducible with pbx_lua, not regular dialplan.

deadlock description:
1. asterisk locks a channel
2. calls function onedigit_goto
3. calls ast_goto_if_exists funciton
4. checks ast_exists_extension -> pbx_extension_helper
5. pbx_extension_helper calls pbx_find_extension
6. Then asterisk starts autoservice in a new thread
7. autoservice run tries to lock the channel again

Because our channel is locked already, autoservice can't lock.
Autoservice can't lock -> autoservice stop is waiting forever.
onedigit_goto waits for autoservice stop.

Resolves: https://github.com/asterisk/asterisk/issues/1335
This commit is contained in:
Alexey Khabulyak
2025-08-04 17:48:57 +03:00
parent 4705601f17
commit 09a3c8df70
1 changed files with 4 additions and 3 deletions
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7
apps/app_dial.c
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@@ -1808,7 +1808,10 @@ static struct ast_channel *wait_for_answer(struct ast_channel *in,
if (ast_test_flag64(peerflags, OPT_DTMF_EXIT)) {
const char *context;
ast_channel_lock(in);
context = pbx_builtin_getvar_helper(in, "EXITCONTEXT");
if ((context = pbx_builtin_getvar_helper(in, "EXITCONTEXT"))) {
context = ast_strdupa(context);
}
ast_channel_unlock(in);
if (onedigit_goto(in, context, (char) f->subclass.integer, 1)) {
ast_verb(3, "User hit %c to disconnect call.\n", f->subclass.integer);
*to_answer = 0;
@@ -1817,14 +1820,12 @@ static struct ast_channel *wait_for_answer(struct ast_channel *in,
pa->canceled = 1;
publish_dial_end_event(in, out_chans, NULL, pa->status);
ast_frfree(f);
ast_channel_unlock(in);
if (is_cc_recall) {
ast_cc_completed(in, "CC completed, but the caller used DTMF to exit");
}
SCOPE_EXIT_RTN_VALUE(NULL, "%s: Caller pressed %c to end call\n",
ast_channel_name(in), f->subclass.integer);
}
ast_channel_unlock(in);
}
if (ast_test_flag64(peerflags, OPT_CALLER_HANGUP) &&