diff mbox series

[v4,3/3] fbmem: Prevent invalid virtual screen sizes

Message ID 20220625232703.401821-4-deller@gmx.de (mailing list archive)
State Superseded
Headers show
Series fbcon: Fixes for screen resolution changes | expand

Commit Message

Helge Deller June 25, 2022, 11:27 p.m. UTC 
Prevent that drivers or the user sets the virtual screen resolution
smaller than the physical screen resolution.  This is important, because
otherwise we may access memory outside of the graphics memory area.

Signed-off-by: Helge Deller <deller@gmx.de>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org # v5.4+
---
 drivers/video/fbdev/core/fbmem.c | 6 ++++++
 1 file changed, 6 insertions(+)

--
2.35.3
diff mbox series

Patch

diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index 160389365a36..b6e1d0f2b974 100644
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -1006,6 +1006,12 @@  fb_set_var(struct fb_info *info, struct fb_var_screeninfo *var)
 	if (var->xres < 8 || var->yres < 8)
 		return -EINVAL;

+	/* make sure virtual resolution >= physical resolution */
+	if (var->xres_virtual < var->xres)
+		return -EINVAL;
+	if (var->yres_virtual < var->yres)
+		return -EINVAL;
+
 	/* Too huge resolution causes multiplication overflow. */
 	if (check_mul_overflow(var->xres, var->yres, &unused) ||
 	    check_mul_overflow(var->xres_virtual, var->yres_virtual, &unused))