[PATCH v3 4/4] fbmem: Prevent invalid virtual screen sizes
From: Helge Deller <deller@gmx.de>
Date: 2022-06-25 22:06:48
Also in:
dri-devel
Subsystem:
framebuffer core, framebuffer layer, the rest · Maintainers:
Simona Vetter, Helge Deller, Linus Torvalds
Prevent that drivers or the user sets the virtual screen resolution smaller than the physical screen resolution. This is important, because otherwise we may get accesses 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 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)) --
2.35.3