Messages in this thread | | | Date | Fri, 19 May 2006 11:22:31 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH 5/6] nfs: check all iov segments for correct memory access rights |
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Chuck Lever <cel@netapp.com> wrote: > > +/* > + * Check: > + * 1. All bytes in the user buffers are properly accessible > + * 2. The resulting number of bytes won't overflow ssize_t > + */
hm.
> +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;
do_readv_writev() already checked for negative iov_len, and that's the more appropriate place to do it, rather than duplicating it in each filesystem (or forgetting to!)
So is this check really needed?
> + if (unlikely(!access_ok(type, buf, len))) { > + retval = -EFAULT; > + goto out; > + }
Now what's up here? Why does NFS, at this level, care about the page's virtual address? get_user_pages() will handle that?
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