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From: Thomas Gleixner <tglx@linutronix.de>
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To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>, LKML
 <linux-kernel@vger.kernel.org>
Cc: "Paul E. McKenney" <paulmck@kernel.org>, Boqun Feng
 <boqun.feng@gmail.com>, Jonathan Corbet <corbet@lwn.net>, Prakash Sangappa
 <prakash.sangappa@oracle.com>, Madadi Vineeth Reddy
 <vineethr@linux.ibm.com>, K Prateek Nayak <kprateek.nayak@amd.com>, Steven
 Rostedt <rostedt@goodmis.org>, Sebastian Andrzej Siewior
 <bigeasy@linutronix.de>, Arnd Bergmann <arnd@arndb.de>,
 linux-arch@vger.kernel.org, Randy Dunlap <rdunlap@infradead.org>, Peter
 Zijlstra <peterz@infradead.org>, Ron Geva <rongevarg@gmail.com>, Waiman
 Long <longman@redhat.com>
Subject: Re: [patch V6 06/11] rseq: Implement syscall entry work for time
 slice extensions
In-Reply-To: <6a0344be-e105-4f09-bf41-02940e730293@efficios.com>
References: <20251215155615.870031952@linutronix.de>
 <20251215155709.005777059@linutronix.de>
 <6a0344be-e105-4f09-bf41-02940e730293@efficios.com>
Date: Thu, 18 Dec 2025 23:28:48 +0100
Message-ID: <87ms3fbf1b.ffs@tglx>
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On Tue, Dec 16 2025 at 10:05, Mathieu Desnoyers wrote:
> On 2025-12-15 13:24, Thomas Gleixner wrote:
> [...]
>> 
>> If the code detects inconsistent user space that result in a SIGSEGV for
>> the application.
>
> With these last updates that allow userspace to call arbitrary system
> calls to terminate the grant, the only scenario which triggers SIGSEGV
> is if the put_user() storing to the rseq area fails. Perhaps we should

Nope. There is also the debug path which will catch offenders which
fiddle with the state.

Thanks,

        tglx