From: Martin KaFai Lau <martin.lau@linux.dev>
To: Shankari Anand <shankari.ak0208@gmail.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
bpf <bpf@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>,
Martin KaFai Lau <martin.lau@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
John Fastabend <john.fastabend@gmail.com>,
Andrii Nakryiko <andrii@kernel.org>,
Eduard Zingerman <eddyz87@gmail.com>, Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@fomichev.me>, Hao Luo <haoluo@google.com>,
Jiri Olsa <jolsa@kernel.org>,
syzbot+ad4661d6ca888ce7fe11@syzkaller.appspotmail.com,
Hou Tao <hotforest@gmail.com>
Subject: Re: [PATCH] bpf: restrict verifier access to bpf_lru_node.ref
Date: Wed, 16 Jul 2025 13:02:33 -0700 [thread overview]
Message-ID: <4c9fcc40-9aca-4ac8-9769-1075e2858b8a@linux.dev> (raw)
In-Reply-To: <CAPRMd3m9NtGXfH3kDWLq-Lu63i1ww4znDJ9aG6ho5J3+Ow_bnQ@mail.gmail.com>
On 7/15/25 11:32 PM, Shankari Anand wrote:
>> I think the percpu_freelist used in the regular hashmap should have similar
>> behavior, so may be worth finding a common solution, such as waiting for a rcu
>> gp before reusing it.
> To resolve this, would it make sense to ensure that elements popped
> from the free list are only reused after a grace period? Similar to
> how other parts of the kernel manage safe object reuse.
The reuse behavior has been there for a long time. It had been discussed
before. Please go back to those threads for the background
and the direction that it is going. This thread is a good start:
https://lore.kernel.org/bpf/20250204082848.13471-3-hotforest@gmail.com/
prev parent reply other threads:[~2025-07-16 20:02 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-15 7:57 [PATCH] bpf: restrict verifier access to bpf_lru_node.ref Shankari Anand
2025-07-15 14:49 ` Alexei Starovoitov
2025-07-15 21:26 ` Martin KaFai Lau
2025-07-16 6:32 ` Shankari Anand
2025-07-16 20:02 ` Martin KaFai Lau [this message]
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