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chan_pjsip.c: Fix deadlock potential in fax redirection.

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The chan_pjsip_cng_tone_detected() has the potential to deadlock if an
incoming fax happens during the Playback or similar application.

* Fixed the potential deadlock by not calling ast_async_goto() with the
channel lock held.

* Made always eat the fax detection frame whether there is a fax extension
or not.

ASTERISK-26216
Reported by: Richard Mudgett

Change-Id: I32aecbb4818af646dc5a619f0dc040e9b1f222e5
This commit is contained in:
Richard Mudgett
2016-07-13 18:48:01 -05:00
parent 628e8c91d5
commit 2e1bdc3775
1 changed files with 7 additions and 5 deletions
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12
channels/chan_pjsip.c
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@@ -628,16 +628,19 @@ static struct ast_frame *chan_pjsip_cng_tone_detected(struct ast_sip_session *se
target_context = S_OR(ast_channel_macrocontext(session->channel), ast_channel_context(session->channel));
/* We need to unlock the channel here because ast_exists_extension has the
/*
* We need to unlock the channel here because ast_exists_extension has the
* potential to start and stop an autoservice on the channel. Such action
* is prone to deadlock if the channel is locked.
*
* ast_async_goto() has its own restriction on not holding the channel lock.
*/
ast_channel_unlock(session->channel);
ast_frfree(f);
f = &ast_null_frame;
exists = ast_exists_extension(session->channel, target_context, "fax", 1,
S_COR(ast_channel_caller(session->channel)->id.number.valid,
ast_channel_caller(session->channel)->id.number.str, NULL));
ast_channel_lock(session->channel);
if (exists) {
ast_verb(2, "Redirecting '%s' to fax extension due to CNG detection\n",
ast_channel_name(session->channel));
@@ -646,12 +649,11 @@ static struct ast_frame *chan_pjsip_cng_tone_detected(struct ast_sip_session *se
ast_log(LOG_ERROR, "Failed to async goto '%s' into fax extension in '%s'\n",
ast_channel_name(session->channel), target_context);
}
ast_frfree(f);
f = &ast_null_frame;
} else {
ast_log(LOG_NOTICE, "FAX CNG detected on '%s' but no fax extension in '%s'\n",
ast_channel_name(session->channel), target_context);
}
ast_channel_lock(session->channel);
return f;
}