From: John Fastabend <john.fastabend@gmail.com>
To: Sechang Lim <rhkrqnwk98@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Eduard Zingerman <eddyz87@gmail.com>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Jesper Dangaard Brouer <hawk@kernel.org>,
Shuah Khan <shuah@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
Jiri Olsa <jolsa@kernel.org>,
Emil Tsalapatis <emil@etsalapatis.com>,
Stanislav Fomichev <sdf@fomichev.me>,
Jiayuan Chen <jiayuan.chen@linux.dev>,
Varun R Mallya <varunrmallya@gmail.com>,
Ihor Solodrai <ihor.solodrai@linux.dev>,
bpf@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org
Subject: Re: [PATCH bpf-next v4 1/2] bpf, sockmap: disallow update and delete from tc, xdp, socket_filter and flow_dissector
Date: Tue, 30 Jun 2026 17:07:38 -0700 [thread overview]
Message-ID: <akRZ_e7DJh2aP-2i@john-p8> (raw)
In-Reply-To: <20260630145410.3648099-2-rhkrqnwk98@gmail.com>
On Tue, Jun 30, 2026 at 02:54:05PM +0000, Sechang Lim wrote:
>sock_map_update_common() and __sock_map_delete() hold stab->lock and call
>sock_map_unref() -> sock_map_del_link(), which takes sk_callback_lock for
>write. That gives the order stab->lock -> sk_callback_lock.
>
>The reverse order comes from the SK_SKB stream parser.
>sk_psock_strp_data_ready() holds sk_callback_lock for read, and after the
>verdict tcp_bpf_strp_read_sock() acks the consumed data inline via
>__tcp_cleanup_rbuf(). The ACK goes out egress, where a sched_cls program
>deletes from the sockmap and takes stab->lock:
>
> WARNING: possible circular locking dependency detected
[...]
>A tc, xdp, socket_filter or flow_dissector program has no reason to
>update or delete a sockmap, and redirect does not go through here. Drop
>them from may_update_sockmap() so the verifier rejects it. It also
>closes the matching sockhash inversion.
>
>Suggested-by: John Fastabend <john.fastabend@gmail.com>
>Signed-off-by: Sechang Lim <rhkrqnwk98@gmail.com>
>---
Great lets get this merged and we will separately fix the sockops
issue reported by the bots.
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
next prev parent reply other threads:[~2026-07-01 0:07 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-30 14:54 [PATCH bpf-next v4 0/2] bpf, sockmap: disallow sockmap mutation from tc, xdp, socket_filter and flow_dissector Sechang Lim
2026-06-30 14:54 ` [PATCH bpf-next v4 1/2] bpf, sockmap: disallow update and delete " Sechang Lim
2026-07-01 0:07 ` John Fastabend [this message]
2026-06-30 14:54 ` [PATCH bpf-next v4 2/2] selftests/bpf: drop tc/xdp/flow_dissector/socket_filter sockmap mutation tests Sechang Lim
2026-07-01 0:10 ` John Fastabend
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