From: Baoquan He <bhe@redhat.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Matt Fleming <matt@codeblueprint.co.uk>,
LKML <linux-kernel@vger.kernel.org>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Ingo Molnar <mingo@kernel.org>, Kees Cook <keescook@chromium.org>,
thgarnie@google.com, caoj.fnst@cn.fujitsu.com,
izumi.taku@jp.fujitsu.com
Subject: Re: [PATCH v2 2/2] x86/boot/KASLR: Restrict kernel to be randomized in mirror regions
Date: Wed, 5 Jul 2017 07:16:38 +0800 [thread overview]
Message-ID: <20170704231638.GA19994@x1> (raw)
In-Reply-To: <alpine.DEB.2.20.1707041744510.9000@nanos>
On 07/04/17 at 05:46pm, Thomas Gleixner wrote:
> On Tue, 4 Jul 2017, Matt Fleming wrote:
> > On Tue, 04 Jul, at 04:46:58PM, Thomas Gleixner wrote:
> > > On Tue, 4 Jul 2017, Baoquan He wrote:
> > >
> > > > In fact I just referred to code in setup_arch(). Now I have a question,
> > > > though CONFIG_EFI=y but efi firmware is not enabled,
> > > > boot_params.efi_info.efi_loader_signature should be initilized to 0.
> > > > Then below code is also problematic.
> > > >
> > > > #ifdef CONFIG_EFI
> > > > if (!strncmp((char *)&boot_params.efi_info.efi_loader_signature,
> > > > EFI32_LOADER_SIGNATURE, 4)) {
> > > > set_bit(EFI_BOOT, &efi.flags);
> > > > } else if (!strncmp((char *)&boot_params.efi_info.efi_loader_signature,
> > > > EFI64_LOADER_SIGNATURE, 4)) {
> > > > set_bit(EFI_BOOT, &efi.flags);
> > > > set_bit(EFI_64BIT, &efi.flags);
> > > > }
> > > >
> > > > if (efi_enabled(EFI_BOOT))
> > > > efi_memblock_x86_reserve_range();
> > > > #endif
> > >
> > > Indeed. Matt?
> >
> > It's possibly that I'm missing some context, but boot_params should be
> > zero'd -- the x86 boot protocol requires that the entire data
> > structure be zero'd on allocation.
> >
> > Have I missed something?
>
> No. I misread the code. The strncmp() operates on
> boot_params.efi_info.efi_loader_signature itself, so yes, all is fine.
Sorry, I must be dizzy at late night of yesterday, just gave wrong
answer when questioned.
>
> It's just Baoquans copy and paste wreckage which is busted.
>
> Thanks,
>
> tglx
>
prev parent reply other threads:[~2017-07-04 23:16 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-04 8:04 [PATCH v2 0/2] x86/boot/KASLR: Restrict kernel to be randomized in mirror regions Baoquan He
2017-07-04 8:04 ` [PATCH v2 1/2] x86/boot/KASLR: Adapt process_e820_entry for any type of memory entry Baoquan He
2017-07-05 22:06 ` Kees Cook
2017-07-06 1:21 ` Baoquan He
2017-07-04 8:04 ` [PATCH v2 2/2] x86/boot/KASLR: Restrict kernel to be randomized in mirror regions Baoquan He
2017-07-04 14:00 ` Thomas Gleixner
2017-07-04 14:30 ` Baoquan He
2017-07-04 14:46 ` Thomas Gleixner
2017-07-04 15:36 ` Matt Fleming
2017-07-04 15:46 ` Thomas Gleixner
2017-07-04 23:16 ` Baoquan He [this message]
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