linux-kernel - Re: [PATCH v2 RESEND 1/2] ARM: spectre-v2: Fix potential missing mitigations

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: <20251028162005.bLKC89Hy@linutronix.de>
Date: Tue, 28 Oct 2025 17:20:05 +0100
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: Xie Yuanbin <xieyuanbin1@...wei.com>
Cc: rmk+kernel@...linux.org.uk, linux@...linux.org.uk, rppt@...nel.org,
	vbabka@...e.cz, pfalcato@...e.de, brauner@...nel.org,
	lorenzo.stoakes@...cle.com, kuninori.morimoto.gx@...esas.com,
	tony@...mide.com, arnd@...db.de, akpm@...ux-foundation.org,
	punitagrawal@...il.com, rjw@...ysocki.net, marc.zyngier@....com,
	will@...nel.org, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, liaohua4@...wei.com,
	lilinjie8@...wei.com
Subject: Re: [PATCH v2 RESEND 1/2] ARM: spectre-v2: Fix potential missing
 mitigations

On 2025-10-16 20:16:21 [+0800], Xie Yuanbin wrote:
> Over the past six years, there have been continuous reports of this bug:
…
> 2019.3.19 https://lore.kernel.org/all/20190319203239.gl46fxnfz6gzeeic@linutronix.de/
> 
> To fix it, we must check whether mitigation are needed before enabling
> interrupt(with PREEMPT) or before calling mm_read_lock()(without PREEMPT).
> 
> Fixes: f5fe12b1eaee ("ARM: spectre-v2: harden user aborts in kernel space")

Hmm.
I was moving things back in 2019 but things shifted and this is no
longer required. If I apply both patches (of yours) then it sends a
signal with disabled interrupts which breaks my PREEMPT_RT case.

The requirement is to invoke the mitigation callback of the right CPU.
What about disabling preemption before getting the callback and doing
the invocation?

Sebastian