From: James Chapman <jchapman@katalix.com>
To: Martin KaFai Lau <kafai@fb.com>
Cc: bpf@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
kernel-team@fb.com, netdev@vger.kernel.org
Subject: Re: [PATCH v2 bpf 2/2] bpf: net: Avoid incorrect bpf_sk_reuseport_detach call
Date: Thu, 9 Jul 2020 11:58:33 +0100 [thread overview]
Message-ID: <20200709105833.GA1761@katalix.com> (raw)
In-Reply-To: <20200709061110.4019316-1-kafai@fb.com>
On Wed, Jul 08, 2020 at 23:11:10 -0700, Martin KaFai Lau wrote:
> bpf_sk_reuseport_detach is currently called when sk->sk_user_data
> is not NULL. It is incorrect because sk->sk_user_data may not be
> managed by the bpf's reuseport_array. It has been reported in [1] that,
> the bpf_sk_reuseport_detach() which is called from udp_lib_unhash() has
> corrupted the sk_user_data managed by l2tp.
>
> This patch solves it by using another bit (defined as SK_USER_DATA_BPF)
> of the sk_user_data pointer value. It marks that a sk_user_data is
> managed/owned by BPF.
I have reservations about using a bit in sk_user_data to indicate
ownership of that pointer. But putting that aside, I confirm that the
patch fixes the problem.
Acked-by: James Chapman <jchapman@katalix.com>
Tested-by: James Chapman <jchapman@katalix.com>
Reported-by: syzbot+9f092552ba9a5efca5df@syzkaller.appspotmail.com
next prev parent reply other threads:[~2020-07-09 10:58 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-09 6:10 [PATCH v2 bpf 0/2] bpf: net: Fixes in sk_user_data of reuseport_array Martin KaFai Lau
2020-07-09 6:11 ` [PATCH v2 bpf 1/2] bpf: net: Avoid copying sk_user_data of reuseport_array during sk_clone Martin KaFai Lau
2020-07-09 16:46 ` Jakub Sitnicki
2020-07-09 20:07 ` Daniel Borkmann
2020-07-09 21:27 ` Martin KaFai Lau
2020-07-09 6:11 ` [PATCH v2 bpf 2/2] bpf: net: Avoid incorrect bpf_sk_reuseport_detach call Martin KaFai Lau
2020-07-09 10:58 ` James Chapman [this message]
2020-07-09 18:47 ` Martin KaFai Lau
2020-07-09 20:07 ` [PATCH v2 bpf 0/2] bpf: net: Fixes in sk_user_data of reuseport_array Daniel Borkmann
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