From: Oleg Nesterov <oleg@redhat.com>
To: Kees Cook <kees@kernel.org>
Cc: Jinjie Ruan <ruanjinjie@huawei.com>,
catalin.marinas@arm.com, will@kernel.org, mark.rutland@arm.com,
luto@amacapital.net, wad@chromium.org, peterz@infradead.org,
ada.coupriediaz@arm.com, linusw@kernel.org, yeoreum.yun@arm.com,
kevin.brodsky@arm.com, anshuman.khandual@arm.com,
james.morse@arm.com, thuth@redhat.com, vladimir.murzin@arm.com,
tglx@kernel.org, broonie@kernel.org, liqiang01@kylinos.cn,
ryan.roberts@arm.com, pengcan@kylinos.cn, kmehltretter@gmail.com,
linux-arm-kernel@lists.infradead.org,
Shuah Khan <shuah@kernel.org>,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
linux-hardening@vger.kernel.org
Subject: Re: [PATCH] selftests/ptrace: Add PTRACE_SYSEMU_SINGLESTEP syscall-exit-stop test
Date: Wed, 23 Sep 2026 13:07:09 +0200 [thread overview]
Message-ID: <arOy3YSkb9417Fo_@redhat.com> (raw)
In-Reply-To: <20260922195719.i.211-kees@kernel.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 <kees@kernel.org>
> ---
> 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 <oleg@redhat.com>
WARNING: multiple messages have this Message-ID (diff)
From: Oleg Nesterov <oleg@redhat.com>
To: Kees Cook <kees@kernel.org>
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 <shuah@kernel.org>,
Jinjie Ruan <ruanjinjie@huawei.com>,
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
Subject: Re: [PATCH] selftests/ptrace: Add PTRACE_SYSEMU_SINGLESTEP syscall-exit-stop test
Date: Wed, 23 Sep 2026 13:07:09 +0200 [thread overview]
Message-ID: <arOy3YSkb9417Fo_@redhat.com> (raw)
In-Reply-To: <20260922195719.i.211-kees@kernel.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 <kees@kernel.org>
> ---
> 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 <oleg@redhat.com>
next prev parent reply other threads:[~2026-09-23 11:07 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-22 19:57 [PATCH] selftests/ptrace: Add PTRACE_SYSEMU_SINGLESTEP syscall-exit-stop test Kees Cook
2026-09-22 19:57 ` Kees Cook
2026-09-23 11:07 ` Oleg Nesterov [this message]
2026-09-23 11:07 ` Oleg Nesterov
2026-09-24 4:11 ` Jinjie Ruan
2026-09-24 4:11 ` Jinjie Ruan
2026-09-24 23:56 ` Kees Cook
2026-09-24 23:56 ` Kees Cook
2026-09-28 1:58 ` Jinjie Ruan
2026-09-28 1:58 ` Jinjie Ruan
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