linux-kernel - Re: [patch V4 23/36] rseq: Provide and use rseq_set

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <0a74c723-3d65-4f5f-a7c6-36255e94e6cb@efficios.com>
Date: Thu, 11 Sep 2025 13:13:48 -0400
From: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To: Thomas Gleixner <tglx@...utronix.de>, LKML <linux-kernel@...r.kernel.org>
Cc: Michael Jeanson <mjeanson@...icios.com>, Jens Axboe <axboe@...nel.dk>,
 Peter Zijlstra <peterz@...radead.org>, "Paul E. McKenney"
 <paulmck@...nel.org>, Boqun Feng <boqun.feng@...il.com>,
 Paolo Bonzini <pbonzini@...hat.com>, Sean Christopherson
 <seanjc@...gle.com>, Wei Liu <wei.liu@...nel.org>,
 Dexuan Cui <decui@...rosoft.com>, x86@...nel.org,
 Arnd Bergmann <arnd@...db.de>, Heiko Carstens <hca@...ux.ibm.com>,
 Christian Borntraeger <borntraeger@...ux.ibm.com>,
 Sven Schnelle <svens@...ux.ibm.com>, Huacai Chen <chenhuacai@...nel.org>,
 Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>
Subject: Re: [patch V4 23/36] rseq: Provide and use rseq_set_ids()

On 2025-09-11 12:02, Thomas Gleixner wrote:
> On Thu, Sep 11 2025 at 09:40, Mathieu Desnoyers wrote:
>> On 2025-09-08 17:32, Thomas Gleixner wrote:

[...]

> 
>> Also why does rseq_fork() set it to ~0ULL rather than keep the value
>> from the parent when forking a new process ?
>>
>> Whatever was present in the parent process in the rseq area should
>> still be in the child, including the rseq registration.
>>
>> Or am missing something ?
> 
> Not really. I just made all those cases (install, fork, exec...) behave
> the same way. It's harmless enough, no?
It does prevent validation of the rseq area content across fork in the
child process. I do not expect this to have a significant impact in
practice though.

Thanks,

Mathieu

-- 
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com