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From:   David Laight <David.Laight@ACULAB.COM>
To:     'Kees Cook' <keescook@chromium.org>,
        Andrew Morton <akpm@linux-foundation.org>
CC:     Ariadne Conill <ariadne@dereferenced.org>,
        Michael Kerrisk <mtk.manpages@gmail.com>,
        Matthew Wilcox <willy@infradead.org>,
        "Christian Brauner" <brauner@kernel.org>,
        Rich Felker <dalias@libc.org>,
        Eric Biederman <ebiederm@xmission.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-hardening@vger.kernel.org" <linux-hardening@vger.kernel.org>
Subject: RE: [PATCH] exec: Force single empty string when argv is empty
Thread-Topic: [PATCH] exec: Force single empty string when argv is empty
Thread-Index: AQHYFwALh17Nc4lWIEewOStTbNpbHKx+aiLA
Date:   Tue, 1 Feb 2022 09:17:47 +0000
Message-ID: <78959c88715049a4be00fc75bb333d3a@AcuMS.aculab.com>
References: <20220201000947.2453721-1-keescook@chromium.org>
In-Reply-To: <20220201000947.2453721-1-keescook@chromium.org>
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From: Kees Cook
> Sent: 01 February 2022 00:10
...
> While the initial code searches[6][7] turned up what appeared to be
> mostly corner case tests, trying to that just reject argv == NULL
> (or an immediately terminated pointer list) quickly started tripping[8]
> existing userspace programs.
> 
> The next best approach is forcing a single empty string into argv and
> adjusting argc to match. The number of programs depending on argc == 0
> seems a smaller set than those calling execve with a NULL argv.

Has anyone considered using the pathname for argv[0]?
So converting:
	execl(path, NULL);
into:
	execl(path, path, NULL);

I've not spotted any such suggestion.

	David

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