linux-kernel - Re: setup_boot_APIC_clock() NULL dereference during early boot on reduced hardware platforms

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 for Android: free password hash cracker in your pocket

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

Message-ID: <alpine.DEB.2.21.1908010931550.1788@nanos.tec.linutronix.de>
Date:   Thu, 1 Aug 2019 09:35:33 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Aubrey Li <aubrey.intel@...il.com>
cc:     Daniel Drake <drake@...lessm.com>, x86@...nel.org,
        "Li, Aubrey" <aubrey.li@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>,
        Linux Kernel <linux-kernel@...r.kernel.org>,
        Endless Linux Upstreaming Team <linux@...lessm.com>
Subject: Re: setup_boot_APIC_clock() NULL dereference during early boot on
 reduced hardware platforms

On Thu, 1 Aug 2019, Aubrey Li wrote:
> On Thu, Aug 1, 2019 at 2:26 PM Daniel Drake <drake@...lessm.com> wrote:
> > global_clock_event is NULL here. This is a "reduced hardware" ACPI
> > platform so acpi_generic_reduced_hw_init() has set timer_init to NULL,
> > avoiding the usual codepaths that would set up global_clock_event.
> >
> IIRC, acpi_generic_reduced_hw_init() avoids initializing PIT, the status of
> this legacy device is unknown in ACPI hw-reduced mode.
> 
> > I tried the obvious:
> >  if (!global_clock_event)
> >     return -1;
> >
> No, the platform needs a global clock event, can you turn on some other

Wrong. The kernel boots perfectly fine without a global clock event. But
for that the TSC and LAPIC frequency must be known.

Thanks,

	tglx