Re: Buggy commit tracked to: "Re: [PATCH 2/9] iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c"

Al Viro
2020-10-22T19:27:31Z

On Thu, Oct 22, 2020 at 08:24:58PM +0100, Al Viro wrote:
> On Thu, Oct 22, 2020 at 12:04:52PM -0700, Nick Desaulniers wrote:
>
> > Passing an `unsigned long` as an `unsigned int` does no such
> > narrowing: https://godbolt.org/z/TvfMxe (same vice-versa, just tail
> > calls, no masking instructions).
> > So if rw_copy_check_uvector() is inlined into import_iovec() (looking
> > at the mainline@1028ae406999), then children calls of
> > `rw_copy_check_uvector()` will be interpreting the `nr_segs` register
> > unmodified, ie. garbage in the upper 32b.
>
> FWIW,
>
> void f(unsinged long v)

s/unsinged/unsigned/, obviously...