From: Eduard Zingerman <eddyz87@gmail.com>
To: "Pu Lehui" <pulehui@huaweicloud.com>,
bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
"Björn Töpel" <bjorn@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
Yonghong Song <yonghong.song@linux.dev>,
Martin KaFai Lau <martin.lau@linux.dev>,
John Fastabend <john.fastabend@gmail.com>,
Song Liu <song@kernel.org>, Jiri Olsa <jolsa@kernel.org>,
Emil Tsalapatis <emil@etsalapatis.com>,
Pu Lehui <pulehui@huawei.com>
Subject: Re: [PATCH bpf-next 1/2] bpf: Reject callback subprogs invoke tailcall
Date: Mon, 13 Jul 2026 15:09:45 -0700 [thread overview]
Message-ID: <3e15d4b9ce4e24e94e0a95d3785fcc0c90448c10.camel@gmail.com> (raw)
In-Reply-To: <20260711104727.4023420-2-pulehui@huaweicloud.com>
On Sat, 2026-07-11 at 10:47 +0000, Pu Lehui wrote:
> From: Pu Lehui <pulehui@huawei.com>
>
> Some JIT compilers, such as x86_64, rely on a register to pass the TCC.
> When subprograms of synchronous callback invoke tailcall, C helpers
> invoking bpf callback clobber this register, and the corrupted TCC may
> bypass the TCC limit, leading to infinite tailcall.
>
> Fix this by rejecting tailcall inside all subprogs of sync callback.
> This also cleanly consolidates the existing async and exception callback
> checks into a single unified `is_cb` check.
>
> Reported-by: Sashiko <sashiko-bot@kernel.org>
> Reported-by: Björn Töpel <bjorn@kernel.org>
> Signed-off-by: Pu Lehui <pulehui@huawei.com>
> ---
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
[...]
next prev parent reply other threads:[~2026-07-13 22:09 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-11 10:47 [PATCH bpf-next 0/2] " Pu Lehui
2026-07-11 10:47 ` [PATCH bpf-next 1/2] bpf: " Pu Lehui
2026-07-11 11:33 ` bot+bpf-ci
2026-07-13 22:09 ` Eduard Zingerman [this message]
2026-07-11 10:47 ` [PATCH bpf-next 2/2] selftests/bpf: Add testcases for callback with tailcall Pu Lehui
2026-07-13 22:12 ` Eduard Zingerman
2026-07-14 2:01 ` Pu Lehui
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