linux-kernel - RE: Buggy commit tracked to: "Re: [PATCH 2/9] iov_iter: move rw_copy_check_uvector() into lib/iov

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Date:   Thu, 22 Oct 2020 16:50:04 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Matthew Wilcox' <willy@...radead.org>
CC:     'Christoph Hellwig' <hch@....de>,
        David Hildenbrand <david@...hat.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        "kernel-team@...roid.com" <kernel-team@...roid.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Jens Axboe" <axboe@...nel.dk>, Arnd Bergmann <arnd@...db.de>,
        David Howells <dhowells@...hat.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mips@...r.kernel.org" <linux-mips@...r.kernel.org>,
        "linux-parisc@...r.kernel.org" <linux-parisc@...r.kernel.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>,
        "sparclinux@...r.kernel.org" <sparclinux@...r.kernel.org>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "linux-aio@...ck.org" <linux-aio@...ck.org>,
        "io-uring@...r.kernel.org" <io-uring@...r.kernel.org>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "keyrings@...r.kernel.org" <keyrings@...r.kernel.org>,
        "linux-security-module@...r.kernel.org" 
        <linux-security-module@...r.kernel.org>
Subject: RE: Buggy commit tracked to: "Re: [PATCH 2/9] iov_iter: move
 rw_copy_check_uvector() into lib/iov_iter.c"

From: Matthew Wilcox <willy@...radead.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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