Subject: Re: [PATCH] commit-graph: fix memory leak

From: Ævar Arnfjörð Bjarmason <[email-masked]>
Date: Tue, 07 May 2019 11:49:41 +0200

On Mon, May 06 2019, Josh Steadmon wrote:

> Free the commit graph when verify_commit_graph_lite() reports an error.
> Credit to OSS-Fuzz for finding this leak.
>
> Signed-off-by: Josh Steadmon <[email-masked]>
> ---
>  commit-graph.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/commit-graph.c b/commit-graph.c
> index 66865acbd7..4bce70d35c 100644
> --- a/commit-graph.c
> +++ b/commit-graph.c
> @@ -267,8 +267,10 @@ struct commit_graph *parse_commit_graph(void *graph_map, int fd,
>  		last_chunk_offset = chunk_offset;
>  	}
>
> -	if (verify_commit_graph_lite(graph))
> +	if (verify_commit_graph_lite(graph)) {
> +		free(graph);
>  		return NULL;
> +	}
>
>  	return graph;
>  }

This is obviously correct, FWIW the leak was there before the
verify_commit_graph_lite() refactoring I did, but I read the rest of the
surrounding code (but haven't run valgrind etc.) and it seems to be the
only one.

I wonder in general if there's a more sustainable solution to these
one-at-a-time memory leak fixes we're doing to these
libraries. E.g. marking some tests in the test suite as passing cleanly
with valgrind's leak checker, and adding a test mode to run those tests.