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

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Date:   Mon, 12 Sep 2022 16:14:07 +0100
From:   Lee Jones <lee@...nel.org>
To:     Yonghong Song <yhs@...com>
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 Mon, 12 Sep 2022, Yonghong Song wrote:
> On 9/12/22 2:38 PM, Lee Jones wrote:
> > The documentation for find_vpid() clearly states:
> > 
> 
> No need for the above extra line.

The intentional blank formatting line?

The commit message would look worse without it.

Is this really a blocker?

> >    "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.

I can expand this.

> > 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>

-- 
Lee Jones [李琼斯]