linux-kernel - [patch 0/2] x86/alternatives: Prevent crash in NOP optimizer

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Message-ID: <20231207193859.961361261@linutronix.de>
Date:   Thu,  7 Dec 2023 20:49:22 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     paul.gortmaker@...driver.com, x86@...nel.org,
        regressions@...mhuis.info, richard.purdie@...uxfoundation.org,
        regressions@...ts.linux.dev
Subject: [patch 0/2] x86/alternatives: Prevent crash in NOP optimizer

The following series addresses the regression report from Paul on behalf of
the yocto project. It turns out that the recent changes to alternatives
opened a race window where interrupts are enabled and NOPs are optimized in
place. An interrupt hitting into the modification will observe inconsistent
text and crash and burn.

A 32bit QEMU crashes w/o these fixes reliably within about 50 boot
attempts. With the fix applied it survived close to 600 attempts by
now.

Thanks to Paul for providing all the information!

Thanks,

	tglx