[linux-usb-devel] Re: Finding user/kernel pointer bugs [no html]

[Luca Risolia]

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>                    unsigned int cmd, void* arg)
>  {
>  	struct w9968cf_device* cam;
> +	void __user *user_arg = (void __user *)arg;

The right place to apply this patch is in video_usercopy().

When video_usercopy() is used in the ioctl() method, there is no need
to dereference the arg pointer in ioctl() itself, since one of the purposes
of video_usercopy() is to do this work for us.

Please have a look at definition of the function in videodev.c.

int
video_usercopy(struct inode *inode, struct file *file,
               unsigned int cmd, unsigned long arg,
               int (*func)(struct inode *inode, struct file *file,
                           unsigned int cmd, unsigned void *arg))

What you have patched in your patch is the function pointed
by "func" above, which should already receive the __user pointer to arg.

Luca
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