Re: [PATCH v6 08/22] bootconfig: init: Allow admin to use bootconfig for init command line

[Arvind Sankar]

On Fri, Feb 07, 2020 at 10:03:16AM -0800, Kees Cook wrote:
> > +
> > +	if (ilen) {
> > +		/*
> > +		 * Append supplemental init boot args to saved_command_line
> > +		 * so that user can check what command line options passed
> > +		 * to init.
> > +		 */
> > +		len = strlen(saved_command_line);
> > +		if (!strstr(boot_command_line, " -- ")) {
> > +			strcpy(saved_command_line + len, " -- ");
> > +			len += 4;
> > +		} else
> > +			saved_command_line[len++] = ' ';
> > +
> > +		strcpy(saved_command_line + len, extra_init_args);
> > +	}
> 
> This isn't safe because it will destroy any argument with " -- " in
> quotes and anything after it. For example, booting with:
> 
> thing=on acpi_osi="! -- " other=setting
> 
> will wreck acpi_osi's value and potentially overwrite "other=settings",
> etc.
> 
> (Yes, this seems very unlikely, but you can't treat " -- " as special,
> the command line string must be correct parsed for double quotes, as
> parse_args() does.)
> 

I think it won't overwrite anything, it will just leave out the " -- "
that should have been added?

I wonder if this is necessary, though -- since commit b88c50ac304a ("log
arguments and environment passed to init") the init arguments will be in
the kernel log anyway.