linux-kernel - Re: [PATCH] drivers/media/video/v4l2-compat-ioctl32.c: Check the return value of copy_to

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Message-Id: <201012211925.38201.arnd@arndb.de>
Date:	Tue, 21 Dec 2010 19:25:38 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	Thiago Farina <tfransosi@...il.com>
Cc:	linux-kernel@...r.kernel.org,
	Guennadi Liakhovetski <g.liakhovetski@....de>,
	Mauro Carvalho Chehab <mchehab@...radead.org>,
	linux-media@...r.kernel.org
Subject: Re: [PATCH] drivers/media/video/v4l2-compat-ioctl32.c: Check the return value of copy_to_user

On Tuesday 21 December 2010 02:18:06 Thiago Farina wrote:
> diff --git a/drivers/media/video/v4l2-compat-ioctl32.c b/drivers/media/video/v4l2-compat-ioctl32.c
> index e30e8df..55825ec 100644
> --- a/drivers/media/video/v4l2-compat-ioctl32.c
> +++ b/drivers/media/video/v4l2-compat-ioctl32.c
> @@ -206,7 +206,9 @@ static struct video_code __user *get_microcode32(struct video_code32 *kp)
>          * user address is invalid, the native ioctl will do
>          * the error handling for us
>          */
> -       (void) copy_to_user(up->loadwhat, kp->loadwhat, sizeof(up->loadwhat));
> +       if (copy_to_user(up->loadwhat, kp->loadwhat, sizeof(up->loadwhat)))
> +               return NULL;
> +
>         (void) put_user(kp->datasize, &up->datasize);
>         (void) put_user(compat_ptr(kp->data), &up->data);
>         return up;

Did you read the comment above the code you changed?

You can probably change this function to look at the return code of
copy_to_user, but then you need to treat the put_user return code
the same, and change the comment.

	Arnd
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