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>,
kkd@meta.com, kernel-team@meta.com
Subject: Re: [PATCH bpf-next v1 03/14] bpf: Preserve R0 lineage across helper calls
Date: Sat, 15 Aug 2026 23:36:01 -0700 [thread overview]
Message-ID: <8b473da1bf04294626e74e8e0cd94e3b70f14df3.camel@gmail.com> (raw)
In-Reply-To: <20260816015746.2632990-4-memxor@gmail.com>
On Sun, 2026-08-16 at 03:57 +0200, Kumar Kartikeya Dwivedi wrote:
> check_helper_call() clears all caller-saved registers before taking the
> diagnostic snapshot of R0. This records NOT_INIT as the old state for every
> helper return and loses the lineage of the value held in R0 before the call.
> bpf_diag_record_caller_saved() deliberately skips R0 because the paired
> modification scope is responsible for it.
>
> Open the R0 modification scope before clearing caller-saved registers,
> matching the kfunc, ld_abs, and subprogram call paths.
>
> Reported-by: Sashiko <sashiko-bot@kernel.org>
> Link: https://lore.kernel.org/bpf/20260815073833.A93A91F000E9@smtp.kernel.org/
> Link: https://lore.kernel.org/bpf/48e6f021b89562f68850fe21ef8c78719819b04cf9c4e4f50bc791937d37ace8@mail.kernel.org/
> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
> ---
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
next prev parent reply other threads:[~2026-08-16 6:36 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-16 1:57 [PATCH bpf-next v1 00/14] Follow ups for verifier errors set Kumar Kartikeya Dwivedi
2026-08-16 1:57 ` [PATCH bpf-next v1 01/14] bpf: Correct verifier diagnostic attribution for stack reads Kumar Kartikeya Dwivedi
2026-08-16 6:34 ` Eduard Zingerman
2026-08-16 1:57 ` [PATCH bpf-next v1 02/14] selftests/bpf: Test verifier stack-read diagnostic attribution Kumar Kartikeya Dwivedi
2026-08-16 2:45 ` bot+bpf-ci
2026-08-16 6:35 ` Eduard Zingerman
2026-08-16 1:57 ` [PATCH bpf-next v1 03/14] bpf: Preserve R0 lineage across helper calls Kumar Kartikeya Dwivedi
2026-08-16 2:30 ` bot+bpf-ci
2026-08-16 6:12 ` Eduard Zingerman
2026-08-16 6:36 ` Eduard Zingerman [this message]
2026-08-16 1:57 ` [PATCH bpf-next v1 04/14] bpf: Drop dead spill diagnostic condition Kumar Kartikeya Dwivedi
2026-08-16 6:39 ` Eduard Zingerman
2026-08-16 1:57 ` [PATCH bpf-next v1 05/14] bpf: Use canonical stack argument names in diagnostics Kumar Kartikeya Dwivedi
2026-08-16 6:40 ` Eduard Zingerman
2026-08-16 1:57 ` [PATCH bpf-next v1 06/14] bpf: Correct kfunc argument diagnostics Kumar Kartikeya Dwivedi
2026-08-16 2:45 ` bot+bpf-ci
2026-08-16 6:50 ` Eduard Zingerman
2026-08-16 6:52 ` Eduard Zingerman
2026-08-16 1:57 ` [PATCH bpf-next v1 07/14] selftests/bpf: Test " Kumar Kartikeya Dwivedi
2026-08-16 6:53 ` Eduard Zingerman
2026-08-16 1:57 ` [PATCH bpf-next v1 08/14] bpf: Report non-sleepable kfunc programs accurately Kumar Kartikeya Dwivedi
2026-08-16 2:30 ` bot+bpf-ci
2026-08-16 7:32 ` Eduard Zingerman
2026-08-16 1:57 ` [PATCH bpf-next v1 09/14] selftests/bpf: Test non-sleepable kfunc context Kumar Kartikeya Dwivedi
2026-08-16 2:30 ` bot+bpf-ci
2026-08-16 7:37 ` Eduard Zingerman
2026-08-16 1:57 ` [PATCH bpf-next v1 10/14] bpf: Correct Program Structure diagnostic context Kumar Kartikeya Dwivedi
2026-08-16 2:45 ` bot+bpf-ci
2026-08-16 7:58 ` Eduard Zingerman
2026-08-16 1:57 ` [PATCH bpf-next v1 11/14] bpf: Preserve source attribution without source text Kumar Kartikeya Dwivedi
2026-08-16 8:01 ` Eduard Zingerman
2026-08-16 1:57 ` [PATCH bpf-next v1 12/14] selftests/bpf: Test Program Structure diagnostic context Kumar Kartikeya Dwivedi
2026-08-16 8:06 ` Eduard Zingerman
2026-08-16 1:57 ` [PATCH bpf-next v1 13/14] bpf: Distinguish function references in policy diagnostics Kumar Kartikeya Dwivedi
2026-08-16 8:09 ` Eduard Zingerman
2026-08-16 1:57 ` [PATCH bpf-next v1 14/14] selftests/bpf: Test pseudo-function " Kumar Kartikeya Dwivedi
2026-08-16 2:45 ` bot+bpf-ci
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