From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Jiayuan Chen <jiayuan.chen@linux.dev>
Cc: jiayuan.chen@shopee.com, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Jesper Dangaard Brouer <hawk@kernel.org>,
John Fastabend <john.fastabend@gmail.com>,
Stanislav Fomichev <sdf@fomichev.me>,
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>,
Clark Williams <clrkwllms@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@kernel.org>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev
Subject: Re: [PATCH bpf v3 0/2] bpf: cpumap/devmap: fix per-CPU bulk queue races on PREEMPT_RT
Date: Tue, 17 Feb 2026 08:43:03 +0100 [thread overview]
Message-ID: <20260217074303.aWlBuoFG@linutronix.de> (raw)
In-Reply-To: <20260213034018.284146-1-jiayuan.chen@linux.dev>
- xxx@vger.kernel.org
On 2026-02-13 11:40:13 [+0800], Jiayuan Chen wrote:
> On PREEMPT_RT kernels, local_bh_disable() only calls migrate_disable()
> (when PREEMPT_RT_NEEDS_BH_LOCK is not set) and does not disable
> preemption. This means CFS scheduling can preempt a task inside the
> per-CPU bulk queue (bq) operations in cpumap and devmap, allowing
> another task on the same CPU to concurrently access the same bq,
> leading to use-after-free, list corruption, and kernel panics.
>
> Patch 1 fixes the cpumap race in bq_flush_to_queue(), originally
> reported by syzbot [1].
>
> Patch 2 fixes the same class of race in devmap's bq_xmit_all(),
> identified by code inspection after Sebastian Andrzej Siewior pointed
> out that devmap has the same per-CPU bulk queue pattern [2].
…
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Sebastian
prev parent reply other threads:[~2026-02-17 7:43 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-13 3:40 [PATCH bpf v3 0/2] bpf: cpumap/devmap: fix per-CPU bulk queue races on PREEMPT_RT Jiayuan Chen
2026-02-13 3:40 ` [PATCH bpf v3 1/2] bpf: cpumap: fix race in bq_flush_to_queue " Jiayuan Chen
2026-02-13 3:40 ` [PATCH bpf v3 2/2] bpf: devmap: fix race in bq_xmit_all " Jiayuan Chen
2026-02-17 7:42 ` Sebastian Andrzej Siewior
2026-02-17 7:43 ` Sebastian Andrzej Siewior [this message]
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