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

[David Laight]

From: Matthew Wilcox <willy at 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

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