From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Mon, 8 Oct 2018 10:57:36 +0000 (+0200)
Subject: fbdev: sbuslib: integer overflow in sbusfb_ioctl_helper()
X-Git-Tag: v4.20-rc1~47^2~10
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e5017716adb8aa5c01c52386c1b7470101ffe9c5;p=thirdparty%2Fkernel%2Flinux.git

fbdev: sbuslib: integer overflow in sbusfb_ioctl_helper()

The "index + count" addition can overflow.  Both come directly from the
user.  This bug leads to an information leak.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Peter Malone <peter.malone@gmail.com>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Mathieu Malaterre <malat@debian.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
---

diff --git a/drivers/video/fbdev/sbuslib.c b/drivers/video/fbdev/sbuslib.c
index 90c51330969c2..01a7110e61a76 100644
--- a/drivers/video/fbdev/sbuslib.c
+++ b/drivers/video/fbdev/sbuslib.c
@@ -171,7 +171,7 @@ int sbusfb_ioctl_helper(unsigned long cmd, unsigned long arg,
 		    get_user(ublue, &c->blue))
 			return -EFAULT;
 
-		if (index + count > cmap->len)
+		if (index > cmap->len || count > cmap->len - index)
 			return -EINVAL;
 
 		for (i = 0; i < count; i++) {