[PATCH] upload-pack: don't send null character in abort message to the client

SZEDER Gábor· Feb 25, 2024, 18:34 UTC · lore

Since 583b7ea31b (upload-pack/fetch-pack: support side-band communication, 2006-06-21) the abort message sent by upload-pack in case of possible repository corruption ends with a null character. This can be seen in several test cases in 't5530-upload-pack-error.sh' where 'grep <pattern> output.err' often reports "Binary file output.err matches" because of that null character.

The reason for this is that the abort message is defined as a string literal, and we pass its size to the send function as sizeof(abort_msg), which also counts the terminating null character.

Use strlen() instead to avoid sending that terminating null character.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
---
 upload-pack.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Show changes to upload-pack.c +1 −1

diff --git a/upload-pack.c b/upload-pack.c
index 2537affa90..6e0d441ef5 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -463,7 +463,7 @@ static void create_pack_file(struct upload_pack_data *pack_data,
 
  fail:
 	free(output_state);
-	send_client_data(3, abort_msg, sizeof(abort_msg),
+	send_client_data(3, abort_msg, strlen(abort_msg),
 			 pack_data->use_sideband);
 	die("git upload-pack: %s", abort_msg);
 }

-- 
2.44.0.rc1.366.g26e5fbbdb0

Junio C Hamano· Feb 26, 2024, 17:49 UTC · re: SZEDER Gábor · lore

Re: [PATCH] upload-pack: don't send null character in abort message to the client

SZEDER Gábor <szeder.dev@gmail.com> writes:

> Since 583b7ea31b (upload-pack/fetch-pack: support side-band
> communication, 2006-06-21) the abort message sent by upload-pack in
> case of possible repository corruption ends with a null character.

It is so so old that makes me wonder if it is safe to "fix" it, but I cannot think of a sensible way to write a third-party client that may have been working fine and would break when this fix is made.

Show 28 quoted lines

> This can be seen in several test cases in 't5530-upload-pack-error.sh'
> where 'grep <pattern> output.err' often reports "Binary file
> output.err matches" because of that null character.
>
> The reason for this is that the abort message is defined as a string
> literal, and we pass its size to the send function as
> sizeof(abort_msg), which also counts the terminating null character.
>
> Use strlen() instead to avoid sending that terminating null character.
>
> Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
> ---
>  upload-pack.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/upload-pack.c b/upload-pack.c
> index 2537affa90..6e0d441ef5 100644
> --- a/upload-pack.c
> +++ b/upload-pack.c
> @@ -463,7 +463,7 @@ static void create_pack_file(struct upload_pack_data *pack_data,
>  
>   fail:
>  	free(output_state);
> -	send_client_data(3, abort_msg, sizeof(abort_msg),
> +	send_client_data(3, abort_msg, strlen(abort_msg),
>  			 pack_data->use_sideband);
>  	die("git upload-pack: %s", abort_msg);
>  }

patchupload-pack: don't send null character in abort message to the client