From: "Michal Koutný" <mkoutny@suse.com>
To: Tadeusz Struk <tadeusz.struk@linaro.org>
Cc: Tejun Heo <tj@kernel.org>, Zefan Li <lizefan.x@bytedance.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Christian Brauner <brauner@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
cgroups@vger.kernel.org, netdev@vger.kernel.org,
bpf@vger.kernel.org, stable@vger.kernel.org,
linux-kernel@vger.kernel.org,
syzbot+e42ae441c3b10acf9e9d@syzkaller.appspotmail.com
Subject: Re: [PATCH v2] cgroup: serialize css kill and release paths
Date: Mon, 6 Jun 2022 14:39:10 +0200 [thread overview]
Message-ID: <20220606123910.GF6928@blackbody.suse.cz> (raw)
In-Reply-To: <20220603181321.443716-1-tadeusz.struk@linaro.org>
Hello.
On Fri, Jun 03, 2022 at 11:13:21AM -0700, Tadeusz Struk <tadeusz.struk@linaro.org> wrote:
> In such scenario the css_killed_work_fn will be en-queued via
> cgroup_apply_control_disable(cgrp)->kill_css(css), and bail out to
> cgroup_kn_unlock(). Then cgroup_kn_unlock() will call:
> cgroup_put(cgrp)->css_put(&cgrp->self), which will try to enqueue
> css_release_work_fn for the same css instance, causing a list_add
> corruption bug, as can be seen in the syzkaller report [1].
This hypothesis doesn't add up to me (I am sorry).
The kill_css(css) would be a css associated with a subsys (css.ss !=
NULL) whereas css_put(&cgrp->self) is a different css just for the
cgroup (css.ss == NULL).
Michal
next prev parent reply other threads:[~2022-06-06 12:39 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-03 17:34 [PATCH] cgroup: serialize css kill and release paths Tadeusz Struk
2022-06-03 18:06 ` Tadeusz Struk
2022-06-03 18:13 ` [PATCH v2] " Tadeusz Struk
2022-06-03 18:17 ` Tadeusz Struk
2022-06-06 12:39 ` Michal Koutný [this message]
2022-06-07 18:47 ` Tadeusz Struk
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