[PATCH v2 3/4] fbmem: Prevent invalid virtual screen sizes in fb_set_var()
From: Helge Deller <deller@gmx.de>
Date: 2022-07-01 20:22:21
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. Give a kernel WARNing and show the driver name to help locating the buggy driver. Signed-off-by: Helge Deller <deller@gmx.de> Cc: stable@vger.kernel.org # 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