[PATCH 4/5] fbmem: Prevent invalid virtual screen sizes in fb_set_var()
From: Helge Deller <deller@gmx.de>
Date: 2022-06-29 20:00:38
Also in:
dri-devel
Subsystem:
framebuffer core, framebuffer layer, the rest · Maintainers:
Simona Vetter, Helge Deller, Linus Torvalds
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. Signed-off-by: Helge Deller <deller@gmx.de> Cc: stable@vger.kernel.org # v5.4+ --- drivers/video/fbdev/core/fbmem.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index 324f726739c4..222d94e2e0a2 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 (WARN_ON(var->xres_virtual < var->xres)) + var->xres_virtual = var->xres; + if (WARN_ON(var->yres_virtual < var->yres)) + var->yres_virtual = var->yres; + /* 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)) --
2.35.3