Prevent that drivers configure a virtual screen resolution smaller than
the physical screen resolution. This is important, because otherwise we
may access memory outside of the graphics memory area.
Give a kernel WARNing and show the driver name to help locating the buggy
driver.
Signed-off-by: Helge Deller <deller@xxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v5.4+
---
drivers/video/fbdev/core/fbmem.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index 160389365a36..e8f06d26803c 100644
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -1016,6 +1016,18 @@ fb_set_var(struct fb_info *info, struct fb_var_screeninfo *var)
if (ret)
return ret;
+ /* make sure virtual resolution >= physical resolution */
+ if (WARN_ON(var->xres_virtual < var->xres)) {
+ pr_warn("fbcon: Fix up invalid xres %d for %s\n",
+ var->xres_virtual, info->fix.id);
+ var->xres_virtual = var->xres;
+ }
+ if (WARN_ON(var->yres_virtual < var->yres)) {
+ pr_warn("fbcon: Fix up invalid yres %d for %s\n",
+ var->yres_virtual, info->fix.id);
+ var->yres_virtual = var->yres;
+ }
+
if ((var->activate & FB_ACTIVATE_MASK) != FB_ACTIVATE_NOW)
return 0;
--
2.35.3
