netdev - Re: [PATCH bpf] bpf: cpumap: Fix memory leak in cpu_map_update

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Message-ID: <da7ac0a1-5f62-bc0e-8954-d3d1e846fb52@redhat.com>
Date: Tue, 11 Jul 2023 18:06:34 +0200
From: Jesper Dangaard Brouer <jbrouer@...hat.com>
To: Pu Lehui <pulehui@...weicloud.com>, bpf@...r.kernel.org,
 netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: brouer@...hat.com, Alexei Starovoitov <ast@...nel.org>,
 Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>,
 "David S. Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
 Jesper Dangaard Brouer <hawk@...nel.org>,
 John Fastabend <john.fastabend@...il.com>,
 Martin KaFai Lau <martin.lau@...ux.dev>, Song Liu <song@...nel.org>,
 Yonghong Song <yhs@...com>, KP Singh <kpsingh@...nel.org>,
 Stanislav Fomichev <sdf@...gle.com>, Hao Luo <haoluo@...gle.com>,
 Jiri Olsa <jolsa@...nel.org>, Xu Kuohai <xukuohai@...wei.com>,
 Pu Lehui <pulehui@...wei.com>
Subject: Re: [PATCH bpf] bpf: cpumap: Fix memory leak in cpu_map_update_elem

On 11/07/2023 13.58, Pu Lehui wrote:
> From: Pu Lehui <pulehui@...wei.com>
> 
> Syzkaller reported a memory leak as follows:
> 
[...]>
> In the cpu_map_update_elem flow, when kthread_stop is called before
> calling the threadfn of rcpu->kthread, since the KTHREAD_SHOULD_STOP bit
> of kthread has been set by kthread_stop, the threadfn of rcpu->kthread
> will never be executed, and rcpu->refcnt will never be 0, which will
> lead to the allocated rcpu, rcpu->queue and rcpu->queue->queue cannot be
> released.
> 
> Calling kthread_stop before executing kthread's threadfn will return
> -EINTR. We can complete the release of memory resources in this state.
> 
> Fixes: 6710e1126934 ("bpf: introduce new bpf cpu map type BPF_MAP_TYPE_CPUMAP")
> Signed-off-by: Pu Lehui <pulehui@...wei.com>

LGTM, thanks for fixing this.

Acked-by: Jesper Dangaard Brouer <hawk@...nel.org>