Re: [fs/exec] 80bd5afdd8: xfstests.generic.633.fail

[Kees Cook <keescook@chromium.org>]

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On Mon, Jan 31, 2022 at 01:59:40PM -0800, Andrew Morton wrote:
> On Mon, 31 Jan 2022 18:13:44 +0100 Christian Brauner <brauner@kernel.org> wrote:
> 
> > > in other words, the changes that you see CMD_ARGS[0] == NULL for
> > > execveat() seem higher than for path-based exec.
> > > 
> > > To counter that we should probably at least update the execveat()
> > > manpage with a recommendation what CMD_ARGS[0] should be set to if it
> > > isn't allowed to be set to NULL anymore. This is why was asking what
> > > argv[0] is supposed to be if the binary doesn't take any arguments.
> > 
> > Sent a fix to our fstests now replacing the argv[0] as NULL with "".
> 
> As we hit this check so quickly, I'm thinking that Ariadne's patch
> "fs/exec: require argv[0] presence in do_execveat_common()" (which
> added the check) isn't something we'll be able to merge into mainline?

I think the next best would be to mutate an NULL argv into { "", NULL }.
However, I still think we should do the pr_warn().

Thoughts?

-- 
Kees Cook