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Thu, 15 Jan 2026 10:46:08 -0800 (PST) Message-ID: Subject: Re: [PATCH bpf-next 2/2] selftests: bpf: Add test for multiple syncs from linked register From: Eduard Zingerman To: Puranjay Mohan , bpf@vger.kernel.org Cc: Puranjay Mohan , Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Martin KaFai Lau , Kumar Kartikeya Dwivedi , Mykyta Yatsenko , kernel-team@meta.com Date: Thu, 15 Jan 2026 10:46:05 -0800 In-Reply-To: <20260115151143.1344724-3-puranjay@kernel.org> References: <20260115151143.1344724-1-puranjay@kernel.org> <20260115151143.1344724-3-puranjay@kernel.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.58.2 (3.58.2-1.fc43) Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Thu, 2026-01-15 at 07:11 -0800, Puranjay Mohan wrote: > Before the last commit, sync_linked_regs() corrupted the register whose > bounds are being updated by copying known_reg's id to it. The ids are > the same in value but known_reg has the BPF_ADD_CONST flag which is > wrongly copied to reg. >=20 > This later causes issues when creating new links to this reg. > assign_scalar_id_before_mov() sees this BPF_ADD_CONST and gives a new id > to this register and breaks the old links. This is exposed by the added > selftest. >=20 > Signed-off-by: Puranjay Mohan > --- Confirm the test behavior on master vs master+patch #1. Tested-by: Eduard Zingerman [...]