Re: [PATCH 5/6] nfs: check all iov segments for correct memory access rights

[Badari Pulavarty <pbadari@us.ibm.com>]

On Fri, 2006-05-19 at 14:00 -0400, Chuck Lever wrote:

>  
> +/*
> + * Check:
> + * 1.  All bytes in the user buffers are properly accessible
> + * 2.  The resulting number of bytes won't overflow ssize_t
> + */
> +static ssize_t check_access_ok(int type, const struct iovec *iov, unsigned long nr_segs)
> +{
> +	ssize_t count = 0;
> +	ssize_t retval = -EINVAL;
> +	unsigned long seg;
> +
> +	for (seg = 0; seg < nr_segs; seg++) {
> +		void __user *buf = iov[seg].iov_base;
> +		ssize_t len = (ssize_t) iov[seg].iov_len;
> +
> +		if (len < 0)		/* size_t not fitting an ssize_t .. */
> +			goto out;
> +		if (unlikely(!access_ok(type, buf, len))) {
> +			retval = -EFAULT;
> +			goto out;
> +		}
> +		count += len;
> +		if (count < 0)		/* math overflow on the ssize_t */
> +			goto out;
> +	}
> +	retval = count;
> +out:
> +	return retval;
> +}
> +

May be move this to fs/read_write.c and export it - since we do the same
thing there also ?

Thanks,
Badari

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