From 99e9e7d62becd6c7413a9e8fbda7f5b66adb5cbf Mon Sep 17 00:00:00 2001 From: Florian Tobias Schandinat Date: Tue, 22 Sep 2009 16:47:41 -0700 Subject: [PATCH] fb: fix fb_pan_display range check Fix the range check for panning. The current code fails to detect some invalid values (very high ones that can occur if an app tries to move further up/left than 0,0) as the check uses the unknown values for calculation so that an overflow can occur. To fix this it is sufficient to move the calculation to the right side to use only trusted values. Kai Jiang detected this problem and proposed an initial patch. Signed-off-by: Florian Tobias Schandinat Cc: Kai Jiang Cc: Krzysztof Helt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/video/fbmem.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c index a85c818be945..346f257215a7 100644 --- a/drivers/video/fbmem.c +++ b/drivers/video/fbmem.c @@ -871,8 +871,8 @@ fb_pan_display(struct fb_info *info, struct fb_var_screeninfo *var) err = -EINVAL; if (err || !info->fbops->fb_pan_display || - var->yoffset + yres > info->var.yres_virtual || - var->xoffset + info->var.xres > info->var.xres_virtual) + var->yoffset > info->var.yres_virtual - yres || + var->xoffset > info->var.xres_virtual - info->var.xres) return -EINVAL; if ((err = info->fbops->fb_pan_display(var, info))) -- 2.20.1