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Wed, 23 Sep 2026 07:07:25 -0400 X-MC-Unique: _Bbwvj4PNpKWfqYbQKVdtw-1 X-Mimecast-MFC-AGG-ID: _Bbwvj4PNpKWfqYbQKVdtw_1790161641 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 88FA3180A9F6; Wed, 23 Sep 2026 11:07:20 +0000 (UTC) Received: from fedora (headnet05.pony-001.prod.iad2.dc.redhat.com [10.2.32.117]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id 092F818002B6; Wed, 23 Sep 2026 11:07:10 +0000 (UTC) Received: by fedora (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Wed, 23 Sep 2026 13:07:20 +0200 (CEST) Date: Wed, 23 Sep 2026 13:07:09 +0200 From: Oleg Nesterov To: Kees Cook Subject: Re: [PATCH] selftests/ptrace: Add PTRACE_SYSEMU_SINGLESTEP syscall-exit-stop test Message-ID: References: <20260922195719.i.211-kees@kernel.org> MIME-Version: 1.0 In-Reply-To: <20260922195719.i.211-kees@kernel.org> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 X-Mimecast-MFC-PROC-ID: K4U3piq4ob14yCyTwSAhiNbDVzqqvMg0p5bIIcSsf7w_1790161641 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-20260923_120740_574219_D134A72F X-CRM114-Status: GOOD ( 12.95 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, peterz@infradead.org, catalin.marinas@arm.com, linux-hardening@vger.kernel.org, linux-kselftest@vger.kernel.org, will@kernel.org, Shuah Khan , Jinjie Ruan , thuth@redhat.com, vladimir.murzin@arm.com, ryan.roberts@arm.com, anshuman.khandual@arm.com, kevin.brodsky@arm.com, kmehltretter@gmail.com, pengcan@kylinos.cn, broonie@kernel.org, linux-arm-kernel@lists.infradead.org, wad@chromium.org, linusw@kernel.org, linux-kernel@vger.kernel.org, luto@amacapital.net, james.morse@arm.com, tglx@kernel.org, liqiang01@kylinos.cn, yeoreum.yun@arm.com Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 09/22, Kees Cook wrote: > > ptrace(2) states that no syscall-exit-stop occurs when a tracee is > continued with PTRACE_SYSEMU or PTRACE_SYSEMU_SINGLESTEP. arm64 gated > its syscall-exit report on > > flags & (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP) > > and ptrace_resume() clears SYSCALL_TRACE for both SYSEMU requests while > PTRACE_SYSEMU_SINGLESTEP additionally sets TIF_SINGLESTEP, so the > single-step bit alone produced a stop that must not exist. Nothing in > tools/testing/selftests covered this. IOW, this test-case veirifies that in the sequence like the generic code step = report_single_step(work); if (step || work & SYSCALL_WORK_SYSCALL_TRACE) arch_ptrace_report_syscall_exit(regs, step); report_single_step() returns false, right? SYSCALL_TRACE is cleared by the arch neutral code... > Link: https://lore.kernel.org/all/20260922035510.1090299-2-ruanjinjie@huawei.com/ [1] > Assisted-by: LLM > Signed-off-by: Kees Cook > --- > tools/testing/selftests/ptrace/Makefile | 3 +- > .../selftests/ptrace/sysemu_singlestep.c | 176 ++++++++++++++++++ > tools/testing/selftests/ptrace/.gitignore | 1 + > 3 files changed, 179 insertions(+), 1 deletion(-) > create mode 100644 tools/testing/selftests/ptrace/sysemu_singlestep.c Reviewed-by: Oleg Nesterov