Add a check to fix a rare segmentation fault you'd get if ast_frdup couldn't allocate

memory on the first frame being queued in ast_queue_frame.

(closes issue #17882)
Reported by: seanbright
Tested by: seanbright



git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@288005 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/channel.c

@@ -927,7 +927,9 @@ static int __ast_queue_frame(struct ast_channel *chan, struct ast_frame *fin, in
 	AST_LIST_HEAD_INIT_NOLOCK(&frames);
 	for (cur = fin; cur; cur = AST_LIST_NEXT(cur, frame_list)) {
 		if (!(f = ast_frdup(cur))) {
-			ast_frfree(AST_LIST_FIRST(&frames));
+			if (AST_LIST_FIRST(&frames)) {
+				ast_frfree(AST_LIST_FIRST(&frames));
+			}
 			ast_channel_unlock(chan);
 			return -1;
 		}