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

Badari Pulavarty
2006-05-19T18:24:08Z

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