From: Catalin Marinas <catalin.marinas@arm•com>
To: Magnus Karlsson <magnus.karlsson@gmail•com>
Cc: "Daniel Borkmann" <daniel@iogearbox•net>,
kirill.shutemov@linux•intel.com, justin.he@arm•com,
linux-mm@kvack•org,
syzbot <syzbot+9301f2f33873407d5b33@syzkaller•appspotmail.com>,
"Andrii Nakryiko" <andriin@fb•com>,
"Alexei Starovoitov" <ast@kernel•org>,
"Björn Töpel" <bjorn.topel@intel•com>, bpf <bpf@vger•kernel.org>,
"David S. Miller" <davem@davemloft•net>,
hawk@kernel•org, "Jakub Kicinski" <jakub.kicinski@netronome•com>,
"John Fastabend" <john.fastabend@gmail•com>,
"Jonathan Lemon" <jonathan.lemon@gmail•com>,
"Martin KaFai Lau" <kafai@fb•com>,
linux-kernel@vger•kernel.org, "Karlsson,
Magnus" <magnus.karlsson@intel•com>,
"Network Development" <netdev@vger•kernel.org>,
"Song Liu" <songliubraving@fb•com>,
syzkaller-bugs@googlegroups•com, "Yonghong Song" <yhs@fb•com>
Subject: Re: WARNING in wp_page_copy
Date: Tue, 17 Dec 2019 22:38:09 +0000 [thread overview]
Message-ID: <20191217223808.GA14982@mbp> (raw)
In-Reply-To: <CAJ8uoz3yDK8sEE05cKA8siBi-Dc0wtbe1-zYgbz_-pd5t69j8w@mail.gmail.com>
On Tue, Dec 17, 2019 at 04:57:34PM +0100, Magnus Karlsson wrote:
> On Tue, Dec 17, 2019 at 4:40 PM Catalin Marinas <catalin.marinas@arm•com> wrote:
> > On Tue, Dec 17, 2019 at 02:27:22PM +0100, Magnus Karlsson wrote:
> > > On Mon, Dec 16, 2019 at 4:10 PM Magnus Karlsson
> > > <magnus.karlsson@gmail•com> wrote:
> > > > On Mon, Dec 16, 2019 at 4:00 PM Daniel Borkmann <daniel@iogearbox•net> wrote:
> > > > > On Sat, Dec 14, 2019 at 08:20:07AM -0800, syzbot wrote:
> > > > > > syzbot has found a reproducer for the following crash on:
> > > > > >
> > > > > > HEAD commit: 1d1997db Revert "nfp: abm: fix memory leak in nfp_abm_u32_..
> > > > > > git tree: net-next
> > > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=1029f851e00000
> > > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=cef1fd5032faee91
> > > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=9301f2f33873407d5b33
> > > > > > compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> > > > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=119d9fb1e00000
> > > > > >
> > > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > > > > > Reported-by: syzbot+9301f2f33873407d5b33@syzkaller•appspotmail.com
> > > > >
> > > > > Bjorn / Magnus, given xsk below, PTAL, thanks!
> > > >
> > > > Thanks. I will take a look at it right away.
> > > >
> > > > /Magnus
> > >
> > > After looking through the syzcaller report, I have the following
> > > hypothesis that would dearly need some comments from MM-savy people
> > > out there. Syzcaller creates, using mmap, a memory area that is
> >
> > I guess that's not an anonymous mmap() since we don't seem to have a
> > struct page for src in cow_user_page() (the WARN_ON_ONCE path). Do you
> > have more information on the mmap() call?
>
> I have this from the syzcaller logs:
>
> mmap(&(0x7f0000001000/0x2000)=nil, 0x2000, 0xfffffe, 0x12, r8, 0x0)
> getsockopt$XDP_MMAP_OFFSETS(r8, 0x11b, 0x7, &(0x7f0000001300),
> &(0x7f0000000100)=0x60)
>
> The full log can be found at:
> https://syzkaller.appspot.com/x/repro.syz?x=119d9fb1e00000
Thanks. Prior to mmap, we have:
r8 = socket$xdp(0x2c, 0x3, 0x0)
So basically we have an mmap() on a socket descriptor with a subsequent
copy_to_user() writing this range. We do we even end up doing CoW on
such mapping? Maybe the socket code should also implement the .fault()
file op. It needs more digging.
--
Catalin
next prev parent reply other threads:[~2019-12-17 22:38 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-02 17:27 WARNING in wp_page_copy syzbot
2019-12-14 16:20 ` syzbot
2019-12-16 15:00 ` Daniel Borkmann
2019-12-16 15:10 ` Magnus Karlsson
2019-12-17 13:27 ` Magnus Karlsson
2019-12-17 15:40 ` Catalin Marinas
2019-12-17 15:57 ` Magnus Karlsson
2019-12-17 22:38 ` Catalin Marinas [this message]
2019-12-18 15:00 ` Magnus Karlsson
2019-12-18 15:11 ` Kirill A. Shutemov
2019-12-17 20:16 ` syzbot
2020-03-24 2:47 ` syzbot
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