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From:   Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= <toke@toke.dk>
To:     Jakub Kicinski <kuba@kernel.org>, Vlad Buslov <vladbu@nvidia.com>
Cc:     Paolo Abeni <pabeni@redhat.com>,
        Daniel Borkmann <daniel@iogearbox.net>,
        syzbot <syzbot+62e474dd92a35e3060d8@syzkaller.appspotmail.com>,
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        Saeed Mahameed <saeedm@nvidia.com>,
        Maxim Mikityanskiy <maximmi@nvidia.com>
Subject: Re: [syzbot] BUG: corrupted list in netif_napi_add
In-Reply-To: <20211018084201.4c7e5be1@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
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Date:   Mon, 18 Oct 2021 19:40:40 +0200
Message-ID: <87lf2qi63r.fsf@toke.dk>
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Jakub Kicinski <kuba@kernel.org> writes:

> 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?

Well, the other report[0] also kinda looks like the NAPI thread keeps
running after it should have been disabled, so maybe they are in fact
related?

-Toke

[0] https://lore.kernel.org/r/000000000000c1524005cdeacc5f@google.com