Re: [PATCH v9 1/9] iov_iter: add copy_struct_from_iter()

On Thu, Apr 01, 2021 at 09:05:22AM -0700, Linus Torvalds wrote:

On Wed, Mar 31, 2021 at 11:51 PM Omar Sandoval [off-list ref] wrote:

quoted

+ *
+ * The recommended usage is something like the following:
+ *
+ *     if (usize > PAGE_SIZE)
+ *       return -E2BIG;

Maybe this should be more than a recommendation, and just be inside
copy_struct_from_iter(), because otherwise the "check_zeroed_user()"
call might be quite the timesink for somebody who does something
stupid.

I did actually almost send this out with the check in
copy_struct_from_iter(), but decided not to for consistency with
copy_struct_from_user().

openat2() seems to be the only user of copy_struct_from_user() that
doesn't limit to PAGE_SIZE, which is odd given that Aleksa wrote both
openat2() and copy_struct_from_user(). Aleksa, was this intentional?

Thanks,
Omar