[FFmpeg-devel] [PATCH] tools/graph2dot: Don't use sizeof(AVFilterGraph), check allocation

[Jan Ekström]

On Thu, Jul 22, 2021 at 10:05 AM Andreas Rheinhardt
<andreas.rheinhardt at outlook.com> wrote:
>
> Use avfilter_graph_alloc() instead of av_mallocz(sizeof(AVFilterGraph))
> to allocate an AVFilterGraph; this also properly allocates the graph's
> internal. The current code just happened to work because it did not
> make any use of said internal.
>
> Also check the allocation; this fixes Coverity #1292528.
>
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>
> ---
>  tools/graph2dot.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/tools/graph2dot.c b/tools/graph2dot.c
> index d5c1e4e3c7..fe1eedb9f3 100644
> --- a/tools/graph2dot.c
> +++ b/tools/graph2dot.c
> @@ -113,7 +113,7 @@ int main(int argc, char **argv)
>      FILE *outfile           = NULL;
>      FILE *infile            = NULL;
>      char *graph_string      = NULL;
> -    AVFilterGraph *graph = av_mallocz(sizeof(AVFilterGraph));
> +    AVFilterGraph *graph;

I really prefer initializing all values to something known instead of
whatever used to be in that memory block before (if calling the
initializer is possible, right away - otherwise a temporary failure
value such as nullptr), but I know we differ in opinion regarding
this, so let's not go further on this :)

>      char c;
>
>      av_log_set_level(AV_LOG_DEBUG);
> @@ -189,6 +189,12 @@ int main(int argc, char **argv)
>          *p = '\0';
>      }
>
> +    graph = avfilter_graph_alloc();
> +    if (!graph) {
> +        fprintf(stderr, "Memory allocation failure\n");
> +        return 1;
> +    }
> +

LGTM.

Jan