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From: Miklos Szeredi <miklos@szeredi.hu>
To: Ondrej Mosnacek <omosnace@redhat.com>
Cc: syzbot <syzbot+f07cc9be8d1d226947ed@syzkaller.appspotmail.com>,
	andriin@fb.com, Alexei Starovoitov <ast@kernel.org>,
	bpf <bpf@vger.kernel.org>, Daniel Borkmann <daniel@iogearbox.net>,
	James Morris <jmorris@namei.org>,
	john.fastabend@gmail.com, kafai@fb.com,
	KP Singh <kpsingh@chromium.org>,
	Linux kernel mailing list <linux-kernel@vger.kernel.org>,
	Linux Security Module list 
	<linux-security-module@vger.kernel.org>,
	network dev <netdev@vger.kernel.org>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	Song Liu <songliubraving@fb.com>,
	syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
	yhs@fb.com, linux-fsdevel@vger.kernel.org,
	overlayfs <linux-unionfs@vger.kernel.org>
Subject: Re: general protection fault in security_inode_getattr
Date: Fri, 30 Oct 2020 14:02:22 +0100	[thread overview]
Message-ID: <CAJfpegtzQB09ind8tkYzaiu6ODJvhMKj3myxVS75vbjTcOxU8g@mail.gmail.com> (raw)
In-Reply-To: <CAFqZXNvQcjp201ahjLBhYJJCuYqZrYLGDA-wE3hXiJpRNgbTKg@mail.gmail.com>

On Mon, Aug 24, 2020 at 11:00 PM Ondrej Mosnacek <omosnace@redhat.com> wrote:
>
> On Mon, Aug 24, 2020 at 9:37 PM syzbot
> <syzbot+f07cc9be8d1d226947ed@syzkaller.appspotmail.com> wrote:
> > syzbot has found a reproducer for the following issue on:
>
> Looping in fsdevel and OverlayFS maintainers, as this seems to be
> FS/OverlayFS related...

Hmm, the oopsing code is always something like:

All code
========
   0: 1b fe                sbb    %esi,%edi
   2: 49 8d 5e 08          lea    0x8(%r14),%rbx
   6: 48 89 d8              mov    %rbx,%rax
   9: 48 c1 e8 03          shr    $0x3,%rax
   d: 42 80 3c 38 00        cmpb   $0x0,(%rax,%r15,1)
  12: 74 08                je     0x1c
  14: 48 89 df              mov    %rbx,%rdi
  17: e8 bc b4 5b fe        callq  0xfffffffffe5bb4d8
  1c: 48 8b 1b              mov    (%rbx),%rbx
  1f: 48 83 c3 68          add    $0x68,%rbx
  23: 48 89 d8              mov    %rbx,%rax
  26: 48 c1 e8 03          shr    $0x3,%rax
  2a:* 42 80 3c 38 00        cmpb   $0x0,(%rax,%r15,1) <-- trapping instruction
  2f: 74 08                je     0x39
  31: 48 89 df              mov    %rbx,%rdi
  34: e8 9f b4 5b fe        callq  0xfffffffffe5bb4d8
  39: 48 8b 1b              mov    (%rbx),%rbx
  3c: 48 83 c3 0c          add    $0xc,%rbx


And that looks (to me) like the unrolled loop in call_int_hook().  I
don't see how that could be related to overlayfs, though it's
definitely interesting why it only triggers from
overlay->vfs_getattr()->security_inode_getattr()...

Thanks,
Miklos

  reply	other threads:[~2020-10-30 13:02 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-29 20:23 general protection fault in security_inode_getattr syzbot
2020-08-24 19:37 ` syzbot
2020-08-24 21:00   ` Ondrej Mosnacek
2020-10-30 13:02     ` Miklos Szeredi [this message]
2020-10-30 18:42       ` Dmitry Vyukov
2020-10-30 19:21         ` Miklos Szeredi
2020-10-30 19:56           ` Dmitry Vyukov
2020-08-25  0:32 ` syzbot
2020-08-25  0:48   ` Yonghong Song
2022-10-15 17:24 ` [syzbot] " syzbot
2022-10-16 14:52   ` Paul Moore
2022-10-17 14:29     ` Tetsuo Handa
2022-10-17  5:38   ` Yonghong Song
2024-04-01 17:36 ` Andrey Kalachev
2024-04-02 16:01   ` Amir Goldstein
2024-04-19 20:01     ` Andrey Kalachev

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