Fix deadlock potential with ast_set_hangupsource() calls.

Calling ast_set_hangupsource() with the channel lock held can result in a
deadlock because the function also locks the bridged channel.

(issue ASTERISK-19537)

(closes issue AST-891)
Reported by: Guenther Kelleter
Tested by: Guenther Kelleter

(closes issue ASTERISK-19801)
Reported by: Alec Davis
........

Merged revisions 368759 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 368760 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@368772 65c4cc65-6c06-0410-ace0-fbb531ad65f3

1 files changed, 9 insertions, 4 deletions

diff --git a/channels/chan_dahdi.c b/channels/chan_dahdi.c
index e6c39d28e..6c5b00ef0 100644
--- a/channels/chan_dahdi.c
+++ b/channels/chan_dahdi.c
@@ -8955,13 +8955,18 @@ static struct ast_frame *__dahdi_exception(struct ast_channel *ast)
 		f = &p->subs[idx].f;
 		return f;
 	}
+
 	f = dahdi_handle_event(ast);
+	if (!f) {
+		const char *name = ast_strdupa(ast_channel_name(ast));
 
-	/* tell the cdr this zap device hung up */
-	if (f == NULL) {
-		ast_set_hangupsource(ast, ast_channel_name(ast), 0);
+		/* Tell the CDR this DAHDI device hung up */
+		ast_mutex_unlock(&p->lock);
+		ast_channel_unlock(ast);
+		ast_set_hangupsource(ast, name, 0);
+		ast_channel_lock(ast);
+		ast_mutex_lock(&p->lock);
 	}
-
 	return f;
 }