linux-hardening - Re: [PATCH] comedi: Annotate struct comedi_lrange with __counted

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Message-ID: <202310011515.D4C9184@keescook>
Date: Sun, 1 Oct 2023 15:21:27 -0700
From: Kees Cook <keescook@...omium.org>
To: Julia Lawall <julia.lawall@...ia.fr>
Cc: Kees Cook <kees@...nel.org>,
	Christophe JAILLET <christophe.jaillet@...adoo.fr>,
	Ian Abbott <abbotti@....co.uk>,
	H Hartley Sweeten <hsweeten@...ionengravers.com>,
	"Gustavo A. R. Silva" <gustavoars@...nel.org>,
	Nathan Chancellor <nathan@...nel.org>,
	Nick Desaulniers <ndesaulniers@...gle.com>,
	Tom Rix <trix@...hat.com>, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org, linux-hardening@...r.kernel.org,
	llvm@...ts.linux.dev
Subject: Re: [PATCH] comedi: Annotate struct comedi_lrange with __counted_by

On Sun, Oct 01, 2023 at 02:22:17PM -0700, Kees Cook wrote:
> On Sun, Oct 01, 2023 at 02:05:46PM -0700, Kees Cook wrote:
> > On Sun, Oct 01, 2023 at 09:14:02PM +0200, Julia Lawall wrote:
> > > Kees,
> > > 
> > > You can try the following.
> > 
> > Cool! Yeah, this finds the example:
> > 
> > drivers/comedi/drivers/rti800.c:74: struct comedi_lrange: field at offset 0 is the counter for the flex array
> > drivers/comedi/drivers/rti800.c:83: struct comedi_lrange: field at offset 0 is the counter for the flex array
> > drivers/comedi/drivers/rti800.c:92: struct comedi_lrange: field at offset 0 is the counter for the flex array
> > 
> > I'll run it on the whole codebase...
> 
> It found only the struct comedi_lrange instances, but that's good to
> know. :)

On a related note, why doesn't this work?

@allocated@
identifier STRUCT, ARRAY;
expression COUNT;
struct STRUCT *PTR;
identifier ALLOC;
type ELEMENT_TYPE;
@@

        PTR = ALLOC(..., sizeof(\(*PTR\|struct STRUCT\)) +
                         COUNT * sizeof(\(*PTR->ARRAY\|PTR->ARRAY[0]\|ELEMENT_TYPE\)), ...);


minus: parse error: 
  File "alloc.cocci", line 15, column 34, charpos = 485
  around = 'struct',
  whole content =       PTR = ALLOC(..., sizeof(\(*PTR\|struct STRUCT\)) +

if I drop "struct", then it complains about ELEMENT_TYPE...

-Kees

-- 
Kees Cook