Em Thu, 29 Mar 2018 10:40:23 +0200
Hans Verkuil [off-list ref] escreveu:

Hi Mauro,

On 28/03/18 19:59, Mauro Carvalho Chehab wrote:

quoted

At put_v4l2_window32(), it tries to access kp->clips. However,
kp points to an userspace pointer. So, it should be obtained
via get_user(), otherwise it can OOPS:
  

<snip>

quoted

cc: stable@vger.kernel.org
Signed-off-by: Mauro Carvalho Chehab <redacted>
---
 drivers/media/v4l2-core/v4l2-compat-ioctl32.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
index 5198c9eeb348..4312935f1dfc 100644
--- a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
+++ b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c

@@ -101,7 +101,7 @@ static int get_v4l2_window32(struct v4l2_window __user *kp,
 static int put_v4l2_window32(struct v4l2_window __user *kp,
 			     struct v4l2_window32 __user *up)
 {
-	struct v4l2_clip __user *kclips = kp->clips;
+	struct v4l2_clip __user *kclips;
 	struct v4l2_clip32 __user *uclips;
 	compat_caddr_t p;
 	u32 clipcount;

@@ -116,6 +116,8 @@ static int put_v4l2_window32(struct v4l2_window __user *kp,
 	if (!clipcount)
 		return 0;
 
+	if (get_user(kclips, &kp->clips))
+		return -EFAULT;
 	if (get_user(p, &up->clips))
 		return -EFAULT;
 	uclips = compat_ptr(p);
  

Reviewed-by: Hans Verkuil <redacted>

I have no idea why I didn't find this when I tested this with v4l2-compliance,
but the code was certainly wrong.

I built 4.16-rc4 with KASAN enabled. Perhaps, it won't OOPS without
it. Yet, I doubt it would work without this fix.

Thank you for debugging this!

Anytime.

Thanks,
Mauro