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[192.26.29.3]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a977edc0fdsm10886565e9.5.2026.10.27.19.15.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Oct 2026 19:15:21 -0700 (PDT) From: Kumar Kartikeya Dwivedi To: bot+bpf-ci@kernel.org Cc: bpf@vger.kernel.org, ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net, eddyz87@gmail.com, emil@etsalapatis.com, ihor.solodrai@linux.dev, kkd@meta.com, kernel-team@meta.com, martin.lau@kernel.org, yonghong.song@linux.dev, mason@kernel.org Subject: Re: [RFC PATCH bpf-next v1 03/11] bpf: Let a callback unwind into the pad of its helper Date: Wed, 28 Oct 2026 03:15:20 +0100 Message-ID: <20261028021520.1203900-9-memxor@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <64d65cba8dd38be485a909c5b03c403ba78bfb67caf179deab641e22208908a8@mail.kernel.org> References: <64d65cba8dd38be485a909c5b03c403ba78bfb67caf179deab641e22208908a8@mail.kernel.org> X-Mailing-List: bpf@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On Wed Oct 28, 2026 at 2:39 AM CET, bot+bpf-ci wrote: > [...] > TL;DR: > - Tracing (ftrace, kretprobe, fexit) may redirect a pad helper's return > address, so unwind could fall through, possibly causing use-after-free or > bad r0; not yet reachable Right. Every function with a pad is notrace and no kprobe target in the next version, as the verifier lets only fentry attach to a subprog that unwinds, with a test that fexit on bpf_loop() is refused. > - Stale comment in backtrack.c (nit) Fixed in the next version. > [...]