linux-kernel - Re: [PATCH v3 1/1] bpf: Ensure correct locking around vulnerable function find

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Message-ID: <243f7ca6-41e1-7522-a6fc-6a35d8104bb5@fb.com>
Date:   Mon, 12 Sep 2022 15:55:04 +0100
From:   Yonghong Song <yhs@...com>
To:     Lee Jones <lee@...nel.org>
Cc:     linux-kernel@...r.kernel.org, Jiri Olsa <jolsa@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        John Fastabend <john.fastabend@...il.com>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <martin.lau@...ux.dev>,
        Song Liu <song@...nel.org>, KP Singh <kpsingh@...nel.org>,
        Stanislav Fomichev <sdf@...gle.com>,
        Hao Luo <haoluo@...gle.com>, bpf@...r.kernel.org
Subject: Re: [PATCH v3 1/1] bpf: Ensure correct locking around vulnerable
 function find_vpid()



On 9/12/22 2:38 PM, Lee Jones wrote:
> The documentation for find_vpid() clearly states:
>

No need for the above extra line.

>    "Must be called with the tasklist_lock or rcu_read_lock() held."
> 
> Presently we do neither.

Presently we do neither for find_vpid() instance in bpf_task_fd_query().
Add proper rcu_read_lock/unlock() to fix the issue.

> 
> Cc: Jiri Olsa <jolsa@...nel.org>
> Cc: Alexei Starovoitov <ast@...nel.org>
> Cc: Daniel Borkmann <daniel@...earbox.net>
> Cc: John Fastabend <john.fastabend@...il.com>
> Cc: Andrii Nakryiko <andrii@...nel.org>
> Cc: Martin KaFai Lau <martin.lau@...ux.dev>
> Cc: Song Liu <song@...nel.org>
> Cc: Yonghong Song <yhs@...com>
> Cc: KP Singh <kpsingh@...nel.org>
> Cc: Stanislav Fomichev <sdf@...gle.com>
> Cc: Hao Luo <haoluo@...gle.com>
> Cc: bpf@...r.kernel.org
> Fixes: 41bdc4b40ed6f ("bpf: introduce bpf subcommand BPF_TASK_FD_QUERY")
> Signed-off-by: Lee Jones <lee@...nel.org>

Ack with above a few suggestions for the commit message.

Acked-by: Yonghong Song <yhs@...com>