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Message-ID: <20180523084451.GK3438@phenom.ffwll.local>
Date: Wed, 23 May 2018 10:44:51 +0200
From: Daniel Vetter <daniel@...ll.ch>
To: Kees Cook <keescook@...omium.org>
Cc: Daniel Vetter <daniel.vetter@...ll.ch>,
Laura Abbott <labbott@...hat.com>,
Patrik Jakobsson <patrik.r.jakobsson@...il.com>,
David Airlie <airlied@...ux.ie>,
Maling list - DRI developers <dri-devel@...ts.freedesktop.org>,
LKML <linux-kernel@...r.kernel.org>,
Kernel Hardening <kernel-hardening@...ts.openwall.com>
Subject: Re: [PATCH] drm/gma500: Remove VLA
On Fri, May 18, 2018 at 10:58:40AM -0700, Kees Cook wrote:
> On Mon, Apr 9, 2018 at 2:06 PM, Laura Abbott <labbott@...hat.com> wrote:
> >
> > There's an ongoing effort to remove VLAs[1] from the kernel to eventually
> > turn on -Wvla. Switch to a reasonable upper bound for the VLAs in
> > the gma500 driver.
> >
> > [1] https://lkml.org/lkml/2018/3/7/621
> >
> > Signed-off-by: Laura Abbott <labbott@...hat.com>
>
> Reviewed-by: Kees Cook <keescook@...omium.org>
>
> Daniel, can this go via you, or what's the best path for this patch?
Applied to drm-misc-next for 4.19, thanks.
-Daniel
>
> Thanks!
>
> -Kees
>
> > ---
> > This was a little hard to figure out but I think 32 should be a
> > comfortable upper bound based on all the structures I saw. Of course I
> > can't test it.
> > ---
> > drivers/gpu/drm/gma500/psb_intel_sdvo.c | 11 +++++++++--
> > 1 file changed, 9 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/gma500/psb_intel_sdvo.c b/drivers/gpu/drm/gma500/psb_intel_sdvo.c
> > index 84507912be84..3d4fa9f6b94c 100644
> > --- a/drivers/gpu/drm/gma500/psb_intel_sdvo.c
> > +++ b/drivers/gpu/drm/gma500/psb_intel_sdvo.c
> > @@ -429,13 +429,20 @@ static const char *cmd_status_names[] = {
> > "Scaling not supported"
> > };
> >
> > +#define MAX_ARG_LEN 32
> > +
> > static bool psb_intel_sdvo_write_cmd(struct psb_intel_sdvo *psb_intel_sdvo, u8 cmd,
> > const void *args, int args_len)
> > {
> > - u8 buf[args_len*2 + 2], status;
> > - struct i2c_msg msgs[args_len + 3];
> > + u8 buf[MAX_ARG_LEN*2 + 2], status;
> > + struct i2c_msg msgs[MAX_ARG_LEN + 3];
> > int i, ret;
> >
> > + if (args_len > MAX_ARG_LEN) {
> > + DRM_ERROR("Need to increase arg length\n");
> > + return false;
> > + }
> > +
> > psb_intel_sdvo_debug_write(psb_intel_sdvo, cmd, args, args_len);
> >
> > for (i = 0; i < args_len; i++) {
> > --
> > 2.14.3
> >
>
>
>
> --
> Kees Cook
> Pixel Security
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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