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From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Mon, 28 Sep 2020 12:04:14 +0200
Message-ID: <CACT4Y+ZkwMZ3Bu77WGtmOGihNbgspdicEq5d_LA1hDVL=KkZyA@mail.gmail.com>
Subject: Re: WARNING: CPU: 1
To:     Arend Van Spriel <arend.vanspriel@broadcom.com>
Cc:     syzbot <syzbot+3640e696903873858f7e@syzkaller.appspotmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        netdev <netdev@vger.kernel.org>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
        Johannes Berg <johannes@sipsolutions.net>,
        linux-wireless <linux-wireless@vger.kernel.org>
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On Mon, Sep 28, 2020 at 11:31 AM Arend Van Spriel
<arend.vanspriel@broadcom.com> wrote:
>
> On 9/27/2020 10:47 AM, Dmitry Vyukov wrote:
> > On Sun, Sep 27, 2020 at 10:38 AM syzbot
> > <syzbot+3640e696903873858f7e@syzkaller.appspotmail.com> wrote:
> >>
> >> Hello,
> >>
> >> syzbot found the following issue on:
> >>
> >> HEAD commit:    748d1c8a Merge branch 'devlink-Use-nla_policy-to-validate-..
> >> git tree:       net-next
> >> console output: https://syzkaller.appspot.com/x/log.txt?x=13ac3ec3900000
> >> kernel config:  https://syzkaller.appspot.com/x/.config?x=51fb40e67d1e3dec
> >> dashboard link: https://syzkaller.appspot.com/bug?extid=3640e696903873858f7e
> >> compiler:       gcc (GCC) 10.1.0-syz 20200507
> >> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1599be03900000
> >> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=149fd44b900000
> >
> > Based on the reproducer, this looks like some wireless bug.
> > +net/wireless maintainers.
>
> I don't think so looking at this part of the stacktrace:
>
> [   51.814941]  [<ffffffff8465cc95>] macvlan_common_newlink+0xa15/0x1720
> [   51.833542]  [<ffffffff84662548>] macvtap_newlink+0x128/0x230
> [   51.858008]  [<ffffffff85b68bfe>] rtnl_newlink+0xe5e/0x1780
> [   51.925885]  [<ffffffff85b5d32b>] rtnetlink_rcv_msg+0x22b/0xc20
>
> Regards,
> Arend

That's the trace on the oldest release and the bisection was diverged
somewhere midway.
You may see this in the bisection log:
https://syzkaller.appspot.com/text?tag=Log&x=1474aaad900000

Initially it crashed with this warning:
all runs: crashed: WARNING in sta_info_insert_rcu

This function is in net/mac80211/sta_info.c.