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From: Leon Hwang <leon.hwang@linux.dev>
To: Junseo Lim <zirajs7@gmail.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Eduard Zingerman <eddyz87@gmail.com>,
	Kumar Kartikeya Dwivedi <memxor@gmail.com>,
	Andrii Nakryiko <andrii@kernel.org>
Cc: John Fastabend <john.fastabend@gmail.com>,
	Martin KaFai Lau <martin.lau@linux.dev>,
	Song Liu <song@kernel.org>,
	Yonghong Song <yonghong.song@linux.dev>,
	Jiri Olsa <jolsa@kernel.org>,
	Emil Tsalapatis <emil@etsalapatis.com>,
	bpf@vger.kernel.org, Sechang Lim <rhkrqnwk98@gmail.com>,
	"Paul E. McKenney" <paulmck@kernel.org>
Subject: Re: [PATCH bpf v2] bpf: keep trampoline progs alive until image release
Date: Thu, 20 Aug 2026 17:26:18 +0800	[thread overview]
Message-ID: <14c836d6-8919-40f8-8559-bd6048c14316@linux.dev> (raw)
In-Reply-To: <20260820022831.18601-1-zirajs7@gmail.com>

Hi Junseo,

On 20/8/26 10:28, Junseo Lim wrote:
> arch_prepare_bpf_trampoline() embeds program pointers in the generated
> image and passes them to __bpf_prog_enter_recur(). After
> bpf_trampoline_update() replaces the image, bpf_tramp_image_put() can keep
> the old image executable past a normal RCU grace period.
> 
> A detached non-sleepable prog can therefore be freed before a preempted
> task reaches rcu_read_lock_dont_migrate() in __bpf_prog_enter_recur(),
> leading to a use-after-free.
> 
> Keep image-local prog refs and drop them from bpf_tramp_image_free().
> 
> Fixes: e21aa341785c ("bpf: Fix fexit trampoline.")

There was an existing fix [1]. Could you take a look at that fix?

[1]
https://lore.kernel.org/bpf/20260819122252.1782790-1-florent.revest@linux.dev/

Thanks,
Leon

> Reported-by: Sechang Lim <rhkrqnwk98@gmail.com>
> Signed-off-by: Junseo Lim <zirajs7@gmail.com>
> --- [...]

      parent reply	other threads:[~2026-08-20  9:26 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-08-20  2:28 [PATCH bpf v2] bpf: keep trampoline progs alive until image release Junseo Lim
2026-08-20  2:42 ` sashiko-bot
2026-08-20  3:35 ` bot+bpf-ci
2026-08-20  9:26 ` Leon Hwang [this message]

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