[git:media_tree/master] media: v4l2-compat-ioctl32: prevent go past max size

[git:media_tree/master] media: v4l2-compat-ioctl32: prevent go past max size

[Mauro Carvalho Chehab]

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Subject: media: v4l2-compat-ioctl32: prevent go past max size
Author:  Mauro Carvalho Chehab <mchehab@s-opensource.com>
Date:    Wed Apr 11 11:47:32 2018 -0400

As warned by smatch:
	drivers/media/v4l2-core/v4l2-compat-ioctl32.c:879 put_v4l2_ext_controls32() warn: check for integer overflow 'count'

The access_ok() logic should check for too big arrays too.

Cc: stable@vger.kernel.org
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

 drivers/media/v4l2-core/v4l2-compat-ioctl32.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

---

diff --git a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
index 4312935f1dfc..d03a44d89649 100644
--- a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
+++ b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
@@ -871,7 +871,7 @@ static int put_v4l2_ext_controls32(struct file *file,
 	    get_user(kcontrols, &kp->controls))
 		return -EFAULT;
 
-	if (!count)
+	if (!count || count > (U32_MAX/sizeof(*ucontrols)))
 		return 0;
 	if (get_user(p, &up->controls))
 		return -EFAULT;