linux-hardening - Re: [PATCH v2] tty: rfcomm: prefer struct

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Date: Mon, 13 May 2024 12:29:04 -0400
From: Luiz Augusto von Dentz <luiz.dentz@...il.com>
To: Jiri Slaby <jirislaby@...nel.org>
Cc: Erick Archer <erick.archer@...look.com>, Marcel Holtmann <marcel@...tmann.org>, 
	Johan Hedberg <johan.hedberg@...il.com>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
	Kees Cook <keescook@...omium.org>, "Gustavo A. R. Silva" <gustavoars@...nel.org>, 
	Nathan Chancellor <nathan@...nel.org>, Nick Desaulniers <ndesaulniers@...gle.com>, 
	Bill Wendling <morbo@...gle.com>, Justin Stitt <justinstitt@...gle.com>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Geert Uytterhoeven <geert@...ux-m68k.org>, 
	linux-bluetooth@...r.kernel.org, netdev@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org, 
	llvm@...ts.linux.dev
Subject: Re: [PATCH v2] tty: rfcomm: prefer struct_size over open coded arithmetic

Hi Jiri, Eric,

On Mon, May 13, 2024 at 1:07 AM Jiri Slaby <jirislaby@...nel.org> wrote:
>
> On 12. 05. 24, 13:17, Erick Archer wrote:
> > This is an effort to get rid of all multiplications from allocation
> > functions in order to prevent integer overflows [1][2].
> >
> > As the "dl" variable is a pointer to "struct rfcomm_dev_list_req" and
> > this structure ends in a flexible array:
> ...
> > --- a/include/net/bluetooth/rfcomm.h
> > +++ b/include/net/bluetooth/rfcomm.h
> ...
> > @@ -528,12 +527,12 @@ static int rfcomm_get_dev_list(void __user *arg)
> >       list_for_each_entry(dev, &rfcomm_dev_list, list) {
> >               if (!tty_port_get(&dev->port))
> >                       continue;
> > -             (di + n)->id      = dev->id;
> > -             (di + n)->flags   = dev->flags;
> > -             (di + n)->state   = dev->dlc->state;
> > -             (di + n)->channel = dev->channel;
> > -             bacpy(&(di + n)->src, &dev->src);
> > -             bacpy(&(di + n)->dst, &dev->dst);
> > +             di[n].id      = dev->id;
> > +             di[n].flags   = dev->flags;
> > +             di[n].state   = dev->dlc->state;
> > +             di[n].channel = dev->channel;
> > +             bacpy(&di[n].src, &dev->src);
> > +             bacpy(&di[n].dst, &dev->dst);
>
> This does not relate much to "prefer struct_size over open coded
> arithmetic". It should have been in a separate patch.

+1, please split these changes into its own patch so we can apply it separately.

> Other than that, LGTM.
>
> thanks,
> --
> js
> suse labs
>


-- 
Luiz Augusto von Dentz