[PATCH 5.15 06/13] drm/fb-helper: set x/yres_virtual in drm_fb_helper_check_var

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

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

commit 1935f0deb6116dd785ea64d8035eab0ff441255b upstream.

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>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230404194038.472803-1-daniel.vetter@ffwll.ch
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/gpu/drm/drm_fb_helper.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -1327,6 +1327,9 @@ int drm_fb_helper_check_var(struct fb_va
 		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