[PATCH 1/3] drm/fb-helper: set x/yres_virtual in drm_fb_helper_check_var

[PATCH 1/3] drm/fb-helper: set x/yres_virtual in drm_fb_helper_check_var

[Daniel Vetter]

Drivers are supposed to fix this up if needed if they don't outright
reject it. Uncovered by 6c11df58fd1a ("fbmem: Check virtual screen
sizes in fb_set_var()").

Reported-by: syzbot+20dcf81733d43ddff661@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?id=c5faf983bfa4a607de530cd3bb008888bf06cefc
Cc: stable@vger.kernel.org # v5.4+
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Javier Martinez Canillas <javierm@redhat.com>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
---
 drivers/gpu/drm/drm_fb_helper.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 59409820f424..eb4ece3e0027 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -1595,6 +1595,9 @@ int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
 		return -EINVAL;
 	}
 
+	var->xres_virtual = fb->width;
+	var->yres_virtual = fb->height;
+
 	/*
 	 * Workaround for SDL 1.2, which is known to be setting all pixel format
 	 * fields values to zero in some cases. We treat this situation as a
-- 
2.40.0

Re: [PATCH 1/3] drm/fb-helper: set x/yres_virtual in drm_fb_helper_check_var

[Javier Martinez Canillas]

Daniel Vetter <daniel.vetter@ffwll.ch> writes:

> Drivers are supposed to fix this up if needed if they don't outright
> reject it. Uncovered by 6c11df58fd1a ("fbmem: Check virtual screen
> sizes in fb_set_var()").
>

Should have a Fixes: tag ? I understand what was uncovered by that commit
but it help distros to figure out if something has to be cherry-picked by
them. So I believe that would be useful to have it.

The patch looks good to me.

Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat

Re: [PATCH 1/3] drm/fb-helper: set x/yres_virtual in drm_fb_helper_check_var

[Daniel Vetter]

On Wed, Apr 05, 2023 at 12:21:11PM +0200, Javier Martinez Canillas wrote:
> Daniel Vetter <daniel.vetter@ffwll.ch> writes:
> 
> > Drivers are supposed to fix this up if needed if they don't outright
> > reject it. Uncovered by 6c11df58fd1a ("fbmem: Check virtual screen
> > sizes in fb_set_var()").
> >
> 
> Should have a Fixes: tag ? I understand what was uncovered by that commit
> but it help distros to figure out if something has to be cherry-picked by
> them. So I believe that would be useful to have it.
> 
> The patch looks good to me.

The cc: stable should go far enough back for that. Or that was at least my
idea ... I can add the Fixes: back since I had it but dropped it
intentionally because it's not really a bug in the fbmem patch.
-Daniel

> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
> 
> -- 
> Best regards,
> 
> Javier Martinez Canillas
> Core Platforms
> Red Hat
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch