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Mon, 9 Nov 2026 13:43:26 +0000 (UTC) Received: from onestero-thinkpadp1gen7.tpbc.csb (headnet04.pony-001.prod.iad2.dc.redhat.com [10.2.32.116]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id B11AC1956089; Mon, 9 Nov 2026 13:43:23 +0000 (UTC) Received: by onestero-thinkpadp1gen7.tpbc.csb (nbSMTP-1.00) for uid 13628 oleg@redhat.com; Mon, 9 Nov 2026 14:43:26 +0100 (CET) Date: Mon, 9 Nov 2026 14:43:22 +0100 From: Oleg Nesterov To: Will Deacon Cc: Zhao Gongyi , catalin.marinas@arm.com, mark.rutland@arm.com, ruanjinjie@huawei.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] arm64: ptrace: don't warn on missing siginfo in a group-stop Message-ID: References: <20261023110710.10145-1-zhaogongyi@bytedance.com> X-Archived-By: MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 X-Mimecast-MFC-PROC-ID: gHrofnmOB0inXXP8lx-GMDlf6z8FPP7qOnzhUTz-M48_1794231807 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261109_054333_491124_C62CD3E1 X-CRM114-Status: GOOD ( 21.51 ) X-Spam-Score: 0.5 (/) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" X-Spam-Status: No, score=-10.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 Will, sorry for late reply, I was on PTO. On 11/04, Will Deacon wrote: > > > > @@ -588,7 +584,7 @@ static void update_syscall_orig_x0_after_ptrace(struct task_struct *target) > > > * Don't update orig_x0 for a syscall-exit-stop, as x0 now contains the > > > * return value of the system call. > > > */ > > > - if ((info->si_code & ~0x80) == SIGTRAP && > > > + if (info && (info->si_code & ~0x80) == SIGTRAP && > > > target->ptrace_message == PTRACE_EVENTMSG_SYSCALL_EXIT) { > > > return; > > > > LGTM, but I don't understand this arm-specific code. > > Welcome to the club :) Thank you ;) > The original rationale is described in e057b9477232 ("arm64: syscall: > Ensure saved x0 is kept in-sync with tracer updates"), so hopefully that > helps to set the scene. [...snip...] Thanks for your explanations. Yes, I tried to read that and other commits. The only result is that I've managed to convinced myself that more or less I understand why 88b839ce497c and 5a87e8c7f3702 make sense. > So that's the mess we're in and I'm all ears if there's a cleaner way to > sort it out without breaking anything that relies on the fragile semantics > we already have. No, I can't suggest anything better. I think your patches and the fix from Zhao are fine. ---------------------------------------------------------------------------- Now the question... So we had CVE-2026-68171 and then it was rejected: https://lore.kernel.org/linux-cve-announce/2026081123-REJECTED-f1f0@gregkh/ Now we have another one, CVE-2026-90347 https://lore.kernel.org/linux-cve-announce/2026091703-CVE-2026-90347-6f2c@gregkh/ Why? To me the problem looks minor (security wise). Yes, a malicious debugger can fool seccomp. So what? What is the real problem from the scurity perspective? Oleg.