Hi, Ville & all
Thanks for quick reply!
According to your reply, the *info has been checked info earlier, and I have
read the code of framebuffer_check() and related drm_get_format_info() which it
calls, but unfortunatelly, I haven't seen judgement(check) for it. What I only
found related with check is the sentence below (in *drm_format_info() in
drivers/gpu/drm/drm_fourcc.c)：
```
info = __drm_format_info(format);
WARN_ON(!info);
```
But to the best of my knowledge, "WARN_ON" only gives a dump_stack(), not
discontinue the program going on, so it will indeed go to the below line in
framebuffer_check() and raise an error:
```
for (i = 0; i < info->num_planes; i++) {
```
So maybe it will make sense of my commited code.
Looking forward to your reply and guidance.
> From: "Ville Syrjälä"<ville.syrj...@linux.intel.com>
> Date: Fri, Oct 27, 2023, 20:33
> Subject: Re: [PATCH] gpu/drm/drm_framebuffer.c: Add judgement for return
> value of drm_get_format_info().
> To: "Peng Hao"<peng...@dingdao.com>
> Cc: <maarten.lankho...@linux.intel.com>, <mrip...@kernel.org>,
> <tzimmerm...@suse.de>, <airl...@gmail.com>, <dan...@ffwll.ch>,
> <linux-ker...@vger.kernel.org>, <dri-devel@lists.freedesktop.org>
> On Fri, Oct 27, 2023 at 05:19:12PM +0800, Peng Hao wrote:
> > Since drm_get_format_info() may return NULL,
>
> Not in this case since we already checked it earlier.
>
> > so a judgement of return
> > value is needed to add.
> >
> > Signed-off-by: Peng Hao <peng...@dingdao.com>
> > ---
> > drivers/gpu/drm/drm_framebuffer.c | 4 ++++
> > 1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/drm_framebuffer.c
> > b/drivers/gpu/drm/drm_framebuffer.c
> > index aff3746dedfb..be7dd1998c04 100644
> > --- a/drivers/gpu/drm/drm_framebuffer.c
> > +++ b/drivers/gpu/drm/drm_framebuffer.c
> > @@ -194,6 +194,10 @@ static int framebuffer_check(struct drm_device *dev,
> >
> > /* now let the driver pick its own format info */
> > info = drm_get_format_info(dev, r);
> > + if (!info) {
> > + drm_dbg_kms(dev, "no matched format info\n");
> > + return -EFAULT;
> > + }
> >
> > for (i = 0; i < info->num_planes; i++) {
> > unsigned int width = fb_plane_width(r->width, info, i);
> > --
> > 2.37.1
>
> --
> Ville Syrjälä
> Intel
