linux-kernel - Re: [PATCH] x86: Plug racy xAPIC access of CPU hotplug code

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]

Date:	Mon, 27 Jan 2014 21:22:52 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Jan Kiszka <jan.kiszka@...mens.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, Andi Kleen <andi@...stfloor.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: Plug racy xAPIC access of CPU hotplug code

On Mon, Jan 27, 2014 at 08:14:06PM +0100, Jan Kiszka wrote:
> apic_icr_write and its users in smpboot.c were apparently written under
> the assumption that this code would only run during early boot. But
> nowadays we also execute it when onlining a CPU later on while the
> system is fully running. That will make wakeup_cpu_via_init_nmi and,
> thus, also native_apic_icr_write run in plain process context. If we
> migrate the caller to a different CPU at the wrong time or interrupt it
> and write to ICR/ICR2 to send unrelated IPIs, we can end up sending
> INIT, SIPI or NMIs to wrong CPUs.
> 
> Fix this by disabling interrupts during the write to the ICR halves and
> disable preemption around waiting for ICR availability and using it.

If you just want to disable migration use get_cpu()/put_cpu()

-Andi
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/