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

David Laight
2020-10-22T16:50:04Z

From: Matthew Wilcox <willy@infradead.org>
> Sent: 22 October 2020 17:41
>
> 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?

The only copy I can find is:

/usr/include/x86_64-linux-gnu/sys/uio.h:extern ssize_t readv (int __fd, const struct iovec *__iovec, int __count)
/usr/include/x86_64-linux-gnu/sys/uio.h- __wur;

and not surprisingly agrees.
POSIX and/or TOG will (more or less) mandate the prototype.

> > 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);
> > }

I wonder when the high bits of 'fd' get zapped?

David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)