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Date:   Mon, 18 Oct 2021 08:42:01 -0700
From:   Jakub Kicinski <kuba@kernel.org>
To:     Vlad Buslov <vladbu@nvidia.com>
Cc:     Paolo Abeni <pabeni@redhat.com>,
        Daniel Borkmann <daniel@iogearbox.net>,
        syzbot <syzbot+62e474dd92a35e3060d8@syzkaller.appspotmail.com>,
        <andrii@kernel.org>, <ast@kernel.org>, <bpf@vger.kernel.org>,
        <davem@davemloft.net>, <hawk@kernel.org>,
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        <songliubraving@fb.com>, <syzkaller-bugs@googlegroups.com>,
        <yhs@fb.com>, <toke@toke.dk>, <joamaki@gmail.com>,
        Saeed Mahameed <saeedm@nvidia.com>,
        Maxim Mikityanskiy <maximmi@nvidia.com>
Subject: Re: [syzbot] BUG: corrupted list in netif_napi_add
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On Mon, 18 Oct 2021 17:04:19 +0300 Vlad Buslov wrote:
> We got a use-after-free with very similar trace [0] during nightly
> regression. The issue happens when ip link up/down state is flipped
> several times in loop and doesn't reproduce for me manually. The fact
> that it didn't reproduce for me after running test ten times suggests
> that it is either very hard to reproduce or that it is a result of some
> interaction between several tests in our suite.
> 
> [0]:
> 
> [ 3187.779569] mlx5_core 0000:08:00.0 enp8s0f0: Link up
>  [ 3187.890694] ==================================================================
>  [ 3187.892518] BUG: KASAN: use-after-free in __list_add_valid+0xc3/0xf0
>  [ 3187.894132] Read of size 8 at addr ffff8881150b3fb8 by task ip/119618

Hm, not sure how similar it is. This one looks like channel was freed
without deleting NAPI. Do you have list debug enabled?