avfilter/graphparser: Fix leaks when parsing inputs fails

parse_inputs() uses a temporary linked list to parse the labeled inputs
of a filter; said linked list owns its elements (and their names). On
success, the list of unlabeled inputs is appened to the end of the list
of labeled inputs and the new list is returned; yet on failures, nothing
frees the already existing elements of the temporary linked list, leading
to a leak.

This can be triggered by e.g. using '-vf [v][' in the FFmpeg
command-line tool.

This leak seems to exist since 4e781c25b7.

Reviewed-by: Nicolas George <george@nsup.org>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
(cherry picked from commit b3f6dee728)

libavfilter/graphparser.c

@@ -303,8 +303,10 @@ static int parse_inputs(const char **buf, AVFilterInOut **curr_inputs,
         char *name = parse_link_name(buf, log_ctx);
         AVFilterInOut *match;
 
-        if (!name)
+        if (!name) {
+            avfilter_inout_free(&parsed_inputs);
             return AVERROR(EINVAL);
+        }
 
         /* First check if the label is not in the open_outputs list */
         match = extract_inout(name, open_outputs);
@@ -314,6 +316,7 @@ static int parse_inputs(const char **buf, AVFilterInOut **curr_inputs,
         } else {
             /* Not in the list, so add it as an input */
             if (!(match = av_mallocz(sizeof(AVFilterInOut)))) {
+                avfilter_inout_free(&parsed_inputs);
                 av_free(name);
                 return AVERROR(ENOMEM);
             }