[Pkg-shadow-devel] Bug#1032393: Bug#1032393: [PATCH v2 2/2] debian/control: Add libbsd-dev and pkg-config

[Alejandro Colomar]

Hi Paul,

On 3/11/23 20:29, Paul Eggert wrote:
> From 522b2db5619bd26631bd444d208768f740c2fdba Mon Sep 17 00:00:00 2001
> From: Paul Eggert <eggert at cs.ucla.edu>
> Date: Sat, 11 Mar 2023 10:34:21 -0800
> Subject: [PATCH 6/6] Fix su silent truncation
> 
> * src/su.c (check_perms): Do not silently truncate user name.
> Use snprintf instead of strlcpy as the latter doesn't buy much here
> and this avoids depending on strlcpy.
> 
> Signed-off-by: Paul Eggert <eggert at cs.ucla.edu>
> ---
>  src/su.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/src/su.c b/src/su.c
> index 9c134a9b..740d31f9 100644
> --- a/src/su.c
> +++ b/src/su.c
> @@ -658,7 +658,14 @@ static /*@only@*/struct passwd * check_perms (void)
>  		SYSLOG ((LOG_INFO,
>  		         "Change user from '%s' to '%s' as requested by PAM",
>  		         name, tmp_name));
> -		strlcpy (name, tmp_name, sizeof(name));
> +	        int tmp_namelen = snprintf (name, sizeof name, tmp_name);

This will likely trigger a warning about using a variable for the format
string.  Are you sure it's can't have conversion specifiers?  Otherwise,
we should use "%s" (if we go the way of snprintf(3)).

But I suggest adding error using strlcpy(3), since it reads much simpler,
and adding error checking to it.  Anyway, we can't stop depending on
libbsd until we find a solution for readpassphrase(3bsd).

Cheers,

Alex

> +		if (! (0 <= tmp_namelen && tmp_namelen < sizeof name)) {
> +			fprintf (stderr, _("Overlong user name '%s'\n"),
> +				 tmp_name);
> +			SYSLOG ((LOG_NOTICE, "Overlong user name '%s'",
> +				 tmp_name));
> +			su_failure (caller_tty, true);
> +		}
>  		pw = xgetpwnam (name);
>  		if (NULL == pw) {
>  			(void) fprintf (stderr,
> @@ -1213,4 +1220,3 @@ int main (int argc, char **argv)
>  
>  	return (errno == ENOENT ? E_CMD_NOTFOUND : E_CMD_NOEXEC);
>  }
> -
> -- 
> 2.37.2
> 


-- 
<http://www.alejandro-colomar.es/>
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