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From: Stanislav Fomichev <sdf@fomichev.me>
To: Tze-nan Wu <Tze-nan.Wu@mediatek.com>
Cc: netdev@vger.kernel.org, bpf@vger.kernel.org,
	Alexei Starovoitov <ast@kernel.org>,
	alexei.starovoitov@gmail.com, bobule.chang@mediatek.com,
	wsd_upstream@mediatek.com, linux-kernel@vger.kernel.org,
	linux-mediatek@lists.infradead.org,
	Kuniyuki Iwashima <kuniyu@amazon.com>,
	chen-yao.chang@mediatek.com, Yanghui Li <yanghui.li@mediatek.com>,
	Cheng-Jui Wang <cheng-jui.wang@mediatek.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	John Fastabend <john.fastabend@gmail.com>,
	Andrii Nakryiko <andrii@kernel.org>,
	Martin KaFai Lau <martin.lau@linux.dev>,
	Eduard Zingerman <eddyz87@gmail.com>, Song Liu <song@kernel.org>,
	Yonghong Song <yonghong.song@linux.dev>,
	KP Singh <kpsingh@kernel.org>, Hao Luo <haoluo@google.com>,
	Jiri Olsa <jolsa@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	AngeloGioacchino Del Regno
	<angelogioacchino.delregno@collabora.com>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH net v5] bpf, net: Fix a potential race in do_sock_getsockopt()
Date: Fri, 30 Aug 2024 20:29:04 -0700	[thread overview]
Message-ID: <ZtKOAKlNalVLIz2E@mini-arch> (raw)
In-Reply-To: <20240830082518.23243-1-Tze-nan.Wu@mediatek.com>

On 08/30, Tze-nan Wu wrote:
> There's a potential race when `cgroup_bpf_enabled(CGROUP_GETSOCKOPT)` is
> false during the execution of `BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN`, but
> becomes true when `BPF_CGROUP_RUN_PROG_GETSOCKOPT` is called.
> This inconsistency can lead to `BPF_CGROUP_RUN_PROG_GETSOCKOPT` receiving
> an "-EFAULT" from `__cgroup_bpf_run_filter_getsockopt(max_optlen=0)`.
> Scenario shown as below:
> 
>            `process A`                      `process B`
>            -----------                      ------------
>   BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN
>                                             enable CGROUP_GETSOCKOPT
>   BPF_CGROUP_RUN_PROG_GETSOCKOPT (-EFAULT)
> 
> To resolve this, remove the `BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN` macro and
> directly uses `copy_from_sockptr` to ensure that `max_optlen` is always 
> set before `BPF_CGROUP_RUN_PROG_GETSOCKOPT` is invoked.
> 
> Fixes: 0d01da6afc54 ("bpf: implement getsockopt and setsockopt hooks")
> Co-developed-by: Yanghui Li <yanghui.li@mediatek.com>
> Signed-off-by: Yanghui Li <yanghui.li@mediatek.com>
> Co-developed-by: Cheng-Jui Wang <cheng-jui.wang@mediatek.com>
> Signed-off-by: Cheng-Jui Wang <cheng-jui.wang@mediatek.com>
> Signed-off-by: Tze-nan Wu <Tze-nan.Wu@mediatek.com>

Acked-by: Stanislav Fomichev <sdf@fomichev.me>

  reply	other threads:[~2024-08-31  3:29 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-08-30  8:25 [PATCH net v5] bpf, net: Fix a potential race in do_sock_getsockopt() Tze-nan Wu
2024-08-31  3:29 ` Stanislav Fomichev [this message]
2024-08-31 22:06   ` Alexei Starovoitov
2024-09-03 20:10 ` patchwork-bot+netdevbpf

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