Subject: Re: [PATCH v2 08/10] object.c: don't go past "len" under die() in type_from_string_gently()

From: Junio C Hamano <[email-masked]>
Date: Thu, 29 Apr 2021 13:55:14 +0900

Ævar Arnfjörð Bjarmason  <[email-masked]> writes:

> Fix a bug that's been with us ever since type_from_string_gently() was
> split off from type_from_string() in fe8e3b71805 (Refactor
> type_from_string() to allow continuing after detecting an error,
> 2014-09-10).
>
> When the type was invalid and we were in the non-gently mode we'd die,
> and then proceed to run off past the "len" of the buffer we were
> provided with.
>
> Luckily, I think that nothing ever used this function in that way. Any
> non-gentle invocation came via type_from_string(), which was passing a
> buffer with a NIL at the same place as the "len" would take us (we got
> it via strlen()).

NIL???

>
> Signed-off-by: Ævar Arnfjörð Bjarmason <[email-masked]>
> ---
>  object.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/object.c b/object.c
> index 70af833ca1..bad9e17f25 100644
> --- a/object.c
> +++ b/object.c
> @@ -50,7 +50,7 @@ int type_from_string_gently(const char *str, ssize_t len, int gentle)
>  	if (gentle)
>  		return -1;
>  
> -	die(_("invalid object type \"%s\""), str);
> +	die(_("invalid object type \"%.*s\""), (int)len, str);
>  }

This makes total sense.  This is one of the reasons why I hate to
review your topics---many patches in them seem unwarranted churn,
but there are clear gems like this commit buried in late steps in
them so I need to read through them to find these anyway :-)