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

Nick Desaulniers
2020-10-22T17:00:59Z

On Thu, Oct 22, 2020 at 9:40 AM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Thu, Oct 22, 2020 at 04:35:17PM +0000, David Laight wrote:
> > Wait...
> > readv(2) defines:
> > ssize_t readv(int fd, const struct iovec *iov, int iovcnt);
>
> It doesn't really matter what the manpage says. What does the AOSP
> libc header say?

Same: https://android.googlesource.com/platform/bionic/+/refs/heads/master/libc/include/sys/uio.h#38

Theoretically someone could bypass libc to make a system call, right?

>
> > But the syscall is defined as:
> >
> > SYSCALL_DEFINE3(readv, unsigned long, fd, const struct iovec __user *, vec,
> > unsigned long, vlen)
> > {
> > return do_readv(fd, vec, vlen, 0);
> > }
>

--
Thanks,
~Nick Desaulniers