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From:   Alexander Potapenko <glider@google.com>
Date:   Mon, 10 Jan 2022 16:41:39 +0100
Message-ID: <CAG_fn=U_z-J2ZxVKD5CvTkOStfqtZ9eCx4qj0cJfzqz44EjFjA@mail.gmail.com>
Subject: Re: [syzbot] KMSAN: kernel-usb-infoleak in usbnet_write_cmd (3)
To:     Pavel Skripkin <paskripkin@gmail.com>
Cc:     syzbot <syzbot+003c0a286b9af5412510@syzkaller.appspotmail.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        johan@kernel.org, LKML <linux-kernel@vger.kernel.org>,
        USB list <linux-usb@vger.kernel.org>,
        Alan Stern <stern@rowland.harvard.edu>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>
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On Thu, Jan 6, 2022 at 11:17 PM Pavel Skripkin <paskripkin@gmail.com> wrote=
:
>
> On 1/5/22 21:28, syzbot wrote:
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit:    81c325bbf94e kmsan: hooks: do not check memory in kmsan=
_in..
> > git tree:       https://github.com/google/kmsan.git master
> > console output: https://syzkaller.appspot.com/x/log.txt?x=3D14a07163b00=
000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=3D2d8b9a11641=
dc9aa
> > dashboard link: https://syzkaller.appspot.com/bug?extid=3D003c0a286b9af=
5412510
> > compiler:       clang version 14.0.0 (/usr/local/google/src/llvm-git-mo=
norepo 2b554920f11c8b763cd9ed9003f4e19b919b8e1f), GNU ld (GNU Binutils for =
Debian) 2.35.2
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=3D100165dbb=
00000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=3D10c97e77b00=
000
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the co=
mmit:
> > Reported-by: syzbot+003c0a286b9af5412510@syzkaller.appspotmail.com
> >
>
> Heh, I think, more reports like this will appear soon. Syzbot learned
> how to tweak usb read functions return values, I guess?

This has been possible long ago. I think these new reports are related
to fresh KMSAN changes (and also the fact KMSAN was broken for a while
last year, and is now catching up).

> #syz test: https://github.com/google/kmsan.git master
>
>
>
> With regards,
> Pavel Skripkin


--=20
Alexander Potapenko
Software Engineer

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