linux-kernel - RE: [PATCH] generic/633: adapt execveat() invocations

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Date:   Wed, 2 Feb 2022 08:36:05 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Christian Brauner' <brauner@...nel.org>, Eryu Guan <guan@...u.me>,
        "fstests@...r.kernel.org" <fstests@...r.kernel.org>
CC:     Ariadne Conill <ariadne@...eferenced.org>,
        Kees Cook <keescook@...omium.org>,
        Rich Felker <dalias@...c.org>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Matthew Wilcox" <willy@...radead.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Eryu Guan <guaneryu@...il.com>
Subject: RE: [PATCH] generic/633: adapt execveat() invocations

From: Christian Brauner
> Sent: 31 January 2022 17:10
> 
> There's a push by Ariadne to enforce that argv[0] cannot be NULL. So far
> we've allowed this. Fix the execveat() invocations to set argv[0] to the
> name of the file we're about to execute.
> 
...
>  src/idmapped-mounts/idmapped-mounts.c | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/src/idmapped-mounts/idmapped-mounts.c b/src/idmapped-mounts/idmapped-mounts.c
> index 4cf6c3bb..76b559ae 100644
> --- a/src/idmapped-mounts/idmapped-mounts.c
> +++ b/src/idmapped-mounts/idmapped-mounts.c
> @@ -3598,7 +3598,7 @@ static int setid_binaries(void)
>  			NULL,
>  		};
>  		static char *argv[] = {
> -			NULL,
> +			"",
>  		};

Isn't that just plain wrong?
argv[] needs to be terminated by a NULL so you need to add the ""
before the NULL not replace the NULL by it.

Quite how this matches the patch description is another matter...

	David

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