From: "Alexei Starovoitov" <alexei.starovoitov@gmail.com>
To: "Xu Yunxiang" <xyx2021@mail.ustc.edu.cn>, <bpf@vger.kernel.org>
Cc: <daniel@iogearbox.net>, <andrii@kernel.org>, <eddyz87@gmail.com>,
<memxor@gmail.com>, <ameryhung@gmail.com>,
<yonghong.song@linux.dev>, <puranjay@kernel.org>
Subject: Re: [PATCH bpf-next v5 1/2] bpf: Track iterator-owned BTF pointer lifetimes
Date: Tue, 22 Sep 2026 23:31:33 +0000 [thread overview]
Message-ID: <DLM8JHZUINUJ.3V54PKAS0QV9B@gmail.com> (raw)
In-Reply-To: <20260920210432.345758-2-xyx2021@mail.ustc.edu.cn>
On Mon, Sep 21, 2026 at 05:04 AM Xu Yunxiang <xyx2021@mail.ustc.edu.cn> wrote:
> BTF_ID_FLAGS(func, bpf_iter_task_vma_new, KF_ITER_NEW | KF_RCU)
> -BTF_ID_FLAGS(func, bpf_iter_task_vma_next, KF_ITER_NEXT | KF_RET_NULL)
> +BTF_ID_FLAGS(func, bpf_iter_task_vma_next, KF_ITER_NEXT | KF_RET_NULL | KF_ITER_LIFETIME)
> BTF_ID_FLAGS(func, bpf_iter_task_vma_destroy, KF_ITER_DESTROY)
> #ifdef CONFIG_CGROUPS
> BTF_ID_FLAGS(func, bpf_iter_css_task_new, KF_ITER_NEW)
> -BTF_ID_FLAGS(func, bpf_iter_css_task_next, KF_ITER_NEXT | KF_RET_NULL)
> +BTF_ID_FLAGS(func, bpf_iter_css_task_next, KF_ITER_NEXT | KF_RET_NULL | KF_ITER_LIFETIME)
[...]
> -BTF_ID_FLAGS(func, bpf_iter_kmem_cache_next, KF_ITER_NEXT | KF_RET_NULL | KF_SLEEPABLE)
> +BTF_ID_FLAGS(func, bpf_iter_kmem_cache_next,
> + KF_ITER_NEXT | KF_RET_NULL | KF_SLEEPABLE | KF_ITER_LIFETIME)
[...]
> -BTF_ID_FLAGS(func, bpf_iter_dmabuf_next, KF_ITER_NEXT | KF_RET_NULL | KF_SLEEPABLE)
> +BTF_ID_FLAGS(func, bpf_iter_dmabuf_next,
> + KF_ITER_NEXT | KF_RET_NULL | KF_SLEEPABLE | KF_ITER_LIFETIME)
So all four iterators that return a non-rcu struct pointer got the
flag and the only one without it is the testmod iterator added in
patch 2. With opt-in a new iterator that forgets the flag gets the
same UAF.
I feel it's better to do opt-out.
pw-bot: cr
next prev parent reply other threads:[~2026-09-22 23:31 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-20 21:04 [PATCH bpf-next v5 0/2] bpf: Track iterator-owned BTF pointer lifetimes Xu Yunxiang
2026-09-20 21:04 ` [PATCH bpf-next v5 1/2] " Xu Yunxiang
2026-09-20 21:21 ` sashiko-bot
2026-09-22 23:13 ` Amery Hung
2026-09-22 23:30 ` Amery Hung
2026-09-22 23:31 ` Alexei Starovoitov [this message]
2026-09-20 21:04 ` [PATCH bpf-next v5 2/2] selftests/bpf: Test iterator " Xu Yunxiang
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