From: Eduard Zingerman <eddyz87@gmail.com>
To: Kumar Kartikeya Dwivedi <memxor@gmail.com>, bpf@vger.kernel.org
Cc: Sashiko <sashiko-bot@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Emil Tsalapatis <emil@etsalapatis.com>,
Nicholas Carlini <npc@anthropic.com>,
kkd@meta.com, kernel-team@meta.com
Subject: Re: [PATCH bpf v1 7/8] bpf: Reject legacy packet loads from callbacks
Date: Thu, 03 Sep 2026 14:58:02 -0700 [thread overview]
Message-ID: <aa58bed78ecad82b396abffbf512f66891c2e2d2.camel@gmail.com> (raw)
In-Reply-To: <20260903214758.2727663-8-memxor@gmail.com>
On Thu, 2026-09-03 at 23:47 +0200, Kumar Kartikeya Dwivedi wrote:
...
> Global functions are verified independently with a fresh frame zero, so
> an active-frame check cannot identify a global function called from a
> callback. Also check the complete subprogram call graph during stack-depth
> validation and reject a function containing a legacy load when any caller
> is a callback. This covers global and static descendants without making
> has_ld_abs transitive, preserving its per-function BTF return-type check.
> Ordinary uses outside callbacks remain supported.
I agree on a first part, but why is this part necessary?
Return value from a global is modeled as an unknown scalar anyway,
hence ld_{ind,abs} short-circuiting it to return 0 should be fine.
Forgoing globals cuts this patch in half.
...
next prev parent reply other threads:[~2026-09-03 21:58 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-03 21:47 [PATCH bpf v1 0/8] Misc bug fixes - part 2 Kumar Kartikeya Dwivedi
2026-09-03 21:47 ` [PATCH bpf v1 1/8] bpf: Check ancestor frames for rbtree callbacks Kumar Kartikeya Dwivedi
2026-09-03 22:40 ` Eduard Zingerman
2026-09-03 22:56 ` bot+bpf-ci
2026-09-03 21:47 ` [PATCH bpf v1 2/8] selftests/bpf: Check rbtree callback restrictions in subprogs Kumar Kartikeya Dwivedi
2026-09-03 22:56 ` bot+bpf-ci
2026-09-03 21:47 ` [PATCH bpf v1 3/8] bpf: Mark bpf_btf_find_by_name_kind() as sleepable Kumar Kartikeya Dwivedi
2026-09-03 22:15 ` Eduard Zingerman
2026-09-03 21:47 ` [PATCH bpf v1 4/8] selftests/bpf: Test btf lookup helper sleepability Kumar Kartikeya Dwivedi
2026-09-03 21:47 ` [PATCH bpf v1 5/8] bpf: Mark faultable stack helpers as sleepable Kumar Kartikeya Dwivedi
2026-09-03 22:00 ` Eduard Zingerman
2026-09-03 22:56 ` bot+bpf-ci
2026-09-03 21:47 ` [PATCH bpf v1 6/8] selftests/bpf: Check faultable stack helper contexts Kumar Kartikeya Dwivedi
2026-09-03 22:56 ` bot+bpf-ci
2026-09-03 21:47 ` [PATCH bpf v1 7/8] bpf: Reject legacy packet loads from callbacks Kumar Kartikeya Dwivedi
2026-09-03 21:58 ` Eduard Zingerman [this message]
2026-09-04 2:22 ` Alexei Starovoitov
2026-09-03 21:47 ` [PATCH bpf v1 8/8] selftests/bpf: " Kumar Kartikeya Dwivedi
2026-09-04 2:30 ` [PATCH bpf v1 0/8] Misc bug fixes - part 2 patchwork-bot+netdevbpf
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