Add virtual screen size check to drm_fb_helper_check_var() in
order to validate userspace input.
Found by Linux Verification Center (linuxtesting.org) with syzkaller.
Signed-off-by: Andrey Strachuk <strochuk@xxxxxxxxx>
Fixes: 785b93ef8c30 ("drm/kms: move driver specific fb common code to helper functions (v2)")
---
drivers/gpu/drm/drm_fb_helper.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 2d4cee6a10ff..5c8b211769eb 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -1355,6 +1355,12 @@ int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
(drm_format_info_block_height(fb->format, 0) > 1))
return -EINVAL;
+ /* verify that virtual resolution >= physical resolution */
+ if (var->xres_virtual < var->xres)
+ var->xres_virtual = var->xres;
+ if (var->yres_virtual < var->yres)
+ var->yres_virtual = var->yres;
+
/*
* Changes struct fb_var_screeninfo are currently not pushed back
* to KMS, hence fail if different settings are requested.
--
2.25.1
