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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Message-ID: <CAKwvOdnq-yYLcF_coo=jMV-RH-SkuNp_kMB+KCBF5cz3PwiB8g@mail.gmail.com>
Date:   Thu, 22 Oct 2020 10:00:44 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     David Laight <David.Laight@...lab.com>,
        Christoph Hellwig <hch@....de>,
        David Hildenbrand <david@...hat.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        "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"

On Thu, Oct 22, 2020 at 9:40 AM Matthew Wilcox <willy@...radead.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