Subject: Re: [PATCH v3 07/11] reftable: fix NULL derefs in error paths

From: Ævar Arnfjörð Bjarmason <[email-masked]>
Date: Mon, 13 Dec 2021 17:24:54 +0100

On Mon, Dec 13 2021, Han-Wen Nienhuys via GitGitGadget wrote:

> From: Han-Wen Nienhuys <[email-masked]>
>
> Spotted by Coverity.
>
> Signed-off-by: Han-Wen Nienhuys <[email-masked]>
> ---
>  reftable/reader.c | 3 ++-
>  reftable/stack.c  | 3 ++-
>  2 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/reftable/reader.c b/reftable/reader.c
> index 006709a645a..8d308d858f8 100644
> --- a/reftable/reader.c
> +++ b/reftable/reader.c
> @@ -796,6 +796,7 @@ int reftable_reader_print_file(const char *tablename)
>  	reftable_table_from_reader(&tab, r);
>  	err = reftable_table_print(&tab);
>  done:
> -	reftable_reader_free(r);
> +	if (r)
> +		reftable_reader_free(r);
>  	return err;
>  }
> diff --git a/reftable/stack.c b/reftable/stack.c
> index 10dfd370e8e..eb03b6c74f6 100644
> --- a/reftable/stack.c
> +++ b/reftable/stack.c
> @@ -707,7 +707,8 @@ done:
>  	strbuf_release(&temp_tab_file_name);
>  	strbuf_release(&tab_file_name);
>  	strbuf_release(&next_name);
> -	reftable_writer_free(wr);
> +	if (wr)
> +		reftable_writer_free(wr);
>  	return err;
>  }

I'd think this would be better:

diff --git a/reftable/reader.c b/reftable/reader.c
index 006709a645a..3eec915830d 100644
--- a/reftable/reader.c
+++ b/reftable/reader.c
@@ -641,7 +641,8 @@ int reftable_new_reader(struct reftable_reader **p,
 
 void reftable_reader_free(struct reftable_reader *r)
 {
-       reader_close(r);
+       if (r)
+               reader_close(r);
        reftable_free(r);
 }

No?