From: Dave Young <dyoung@redhat.com>
To: Mike Galbraith <efault@gmx.de>
Cc: Baoquan He <bhe@redhat.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
lkml <linux-kernel@vger.kernel.org>,
kexec@lists.infradead.org, linux-efi@vger.kernel.org,
ard.biesheuvel@linaro.org
Subject: Re: [PATCH] x86, kdump: Fix efi=noruntime NULL pointer dereference
Date: Thu, 9 Aug 2018 17:13:33 +0800 [thread overview]
Message-ID: <20180809091333.GA8008@dhcp-128-65.nay.redhat.com> (raw)
In-Reply-To: <1533800010.5087.71.camel@gmx.de>
On 08/09/18 at 09:33am, Mike Galbraith wrote:
> On Thu, 2018-08-09 at 12:21 +0800, Dave Young wrote:
> > Hi Mike,
> >
> > Thanks for the patch!
> > On 08/08/18 at 04:03pm, Mike Galbraith wrote:
> > > When booting with efi=noruntime, we call efi_runtime_map_copy() while
> > > loading the kdump kernel, and trip over a NULL efi.memmap.map. Avoid
> > > that and a useless allocation when the only mapping we can use (1:1)
> > > is not available.
> >
> > At first glance, efi_get_runtime_map_size should return 0 in case
> > noruntime.
>
> What efi does internally at unmap time is to leave everything except
> efi.mmap.map untouched, setting it to NULL and turning off EFI_MEMMAP,
> rendering efi.mmap.map accessors useless/unsafe without first checking
> EFI_MEMMAP.
Probably the x86 efi_init should reset nr_map to zero in case runtime is
disabled. But let's see how Ard thinks about this and cc linux-efi.
As for efi_get_runtime_map_size, it was introduced for x86 kexec use.
for copying runtime maps, so I think it is reasonable this function
return zero in case no runtime.
Thanks
Dave
next prev parent reply other threads:[~2018-08-09 9:13 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-08 14:03 [PATCH] x86, kdump: Fix efi=noruntime NULL pointer dereference Mike Galbraith
2018-08-09 4:21 ` Dave Young
2018-08-09 5:05 ` Mike Galbraith
2018-08-09 7:33 ` Mike Galbraith
2018-08-09 9:13 ` Dave Young [this message]
2018-08-21 13:39 ` Ard Biesheuvel
2018-08-22 10:23 ` Dave Young
2018-08-23 3:57 ` Dave Young
2018-08-23 4:08 ` Mike Galbraith
2018-08-24 4:48 ` Mike Galbraith
2018-08-24 6:49 ` Dave Young
2018-08-10 8:45 ` Dave Young
2018-08-10 10:23 ` Mike Galbraith
2018-08-10 10:28 ` Dave Young
2018-08-10 17:39 ` Mike Galbraith
2018-08-15 3:59 ` Dave Young
2018-08-15 4:57 ` Mike Galbraith
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