From: Andrzej Hunt <andrzej@ahunt.org>
Date: Thu, 15 Jul 2021 17:37:02 GMT
Subject: Re: [PATCH v2 3/4] SANITIZE tests: fix memory leaks in t5701*, add to whitelist
Message-ID: <c6c7cfea-8292-2034-f9d6-de350e6e2692@ahunt.org>
In-Reply-To: <patch-3.4-b7fb5d5a56-20210714T172251Z-avarab@gmail.com>



On 14/07/2021 19:23, Ævar Arnfjörð Bjarmason wrote:
> Fix a memory leak in a2ba162cda (object-info: support for retrieving
> object info, 2021-04-20) which appears to have been based on a
> misunderstanding of how the pkt-line.c API works, there is no need to
> strdup() input to, it's just a printf()-like format function.
> 
> This fixes a potentially large memory leak, since the number of OID
> lines the "object-info" call can be arbitrarily large (or a small one
> if the request is small).
> 
> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
> ---
>   protocol-caps.c      | 5 +++--
>   t/t5701-git-serve.sh | 1 +
>   2 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/protocol-caps.c b/protocol-caps.c
> index 13a9e63a04..901b6795e4 100644
> --- a/protocol-caps.c
> +++ b/protocol-caps.c
> @@ -69,9 +69,10 @@ static void send_info(struct repository *r, struct packet_writer *writer,
>   			}
>   		}
>   
> -		packet_writer_write(writer, "%s",
> -				    strbuf_detach(&send_buffer, NULL));
> +		packet_writer_write(writer, "%s", send_buffer.buf);
> +		strbuf_reset(&send_buffer);
>   	}
> +	strbuf_release(&send_buffer);
>   }

Good catch! strbuf's seem to be a common source of leak, where either 
the release is forgotten or detach is used incorrectly - and I'm tempted 
to try and implement some automated checks to catch those (I wonder if 
coccicheck is powerful enough for this?).

>   ...