From: Dan Carpenter <dan.carpen...@oracle.com>

[ Upstream commit e5017716adb8aa5c01c52386c1b7470101ffe9c5 ]

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.carpen...@oracle.com>
Cc: Peter Malone <peter.mal...@gmail.com>
Cc: Philippe Ombredanne <pombreda...@nexb.com>
Cc: Mathieu Malaterre <ma...@debian.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnier...@samsung.com>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 drivers/video/fbdev/sbuslib.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

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++) {
-- 
2.20.1

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