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Groups > linux.kernel > #1683121
| From | Matt Fleming <matt@codeblueprint.co.uk> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH] x86/boot/KASLR: exclude EFI_BOOT_SERVICES_{CODE|DATA} from KASLR's choice |
| Date | 2017-07-07 13:00 +0200 |
| Message-ID | <u0z9n-2TL-3@gated-at.bofh.it> (permalink) |
| References | <u0aun-1Sl-37@gated-at.bofh.it> <u0gq6-6g7-15@gated-at.bofh.it> <u0rOx-6mN-7@gated-at.bofh.it> <u0uMp-8mP-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Fri, 07 Jul, at 06:11:24AM, Naoya Horiguchi wrote:
> On Fri, Jul 07, 2017 at 11:07:59AM +0800, Baoquan He wrote:
> > On 07/06/17 at 03:57pm, Matt Fleming wrote:
> > > On Thu, 06 Jul, at 08:31:07AM, Naoya Horiguchi wrote:
> > > > + for (i = 0; i < nr_desc; i++) {
> > > > + md = (efi_memory_desc_t *)(pmap + (i * e->efi_memdesc_size));
> > > > +
> > > > + /*
> > > > + * EFI_BOOT_SERVICES_{CODE|DATA} are avoided because boot
> > > > + * services regions could be accessed after ExitBootServices()
> > > > + * due to the workaround for buggy firmware.
> > > > + */
> > > > + if (!(md->type == EFI_LOADER_CODE ||
> > > > + md->type == EFI_LOADER_DATA ||
> > > > + md->type == EFI_CONVENTIONAL_MEMORY))
> > > > + continue;
> > >
> > > Wouldn't it make more sense to *only* use EFI_CONVENTIONAL_MEMORY?
> > >
> > > You can't re-use EFI_LOADER_* regions because the kaslr code is run so
> > > early in boot that you've no idea if data the kernel will need is in
> > > those EFI_LOADER_* regions.
> > >
> > > For example, we pass struct setup_data objects inside of
> > > EFI_LOADER_DATA regions.
> >
> > It doesn't matter because we have tried to avoid those memory setup_data
> > resides in in mem_avoid_overlap(). Here discarding EFI_LOADER_* could
> > discard the whole regions while setup_data could occupy small part of
> > them.
>
> Hi Matt, Baoquan,
>
> I added these three checks to accept any regions corresponding to
> E820_TYPE_RAM except EFI_BOOT_SERVICES_*, just thinking of that it's minimum
> surprising. Baoquan gave a good justification on that, so I'll leave it
> as-is in next version.
I disagree. The least surprising option would be to use the region
type that everyone (boot loader, kernel, firmware) agrees is free:
EFI_CONVENTIONAL_MEMORY.
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[PATCH] x86/boot/KASLR: exclude EFI_BOOT_SERVICES_{CODE|DATA} from KASLR's choice Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2017-07-06 10:40 +0200
Re: [PATCH] x86/boot/KASLR: exclude EFI_BOOT_SERVICES_{CODE|DATA} from KASLR's choice Chao Fan <fanc.fnst@cn.fujitsu.com> - 2017-07-06 11:20 +0200
Re: [PATCH] x86/boot/KASLR: exclude EFI_BOOT_SERVICES_{CODE|DATA} from KASLR's choice Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2017-07-06 11:30 +0200
Re: [PATCH] x86/boot/KASLR: exclude EFI_BOOT_SERVICES_{CODE|DATA} from KASLR's choice Chao Fan <fanc.fnst@cn.fujitsu.com> - 2017-07-06 11:40 +0200
Re: [PATCH] x86/boot/KASLR: exclude EFI_BOOT_SERVICES_{CODE|DATA} from KASLR's choice Baoquan He <bhe@redhat.com> - 2017-07-06 11:20 +0200
Re: [PATCH] x86/boot/KASLR: exclude EFI_BOOT_SERVICES_{CODE|DATA} from KASLR's choice Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2017-07-06 11:40 +0200
Re: [PATCH] x86/boot/KASLR: exclude EFI_BOOT_SERVICES_{CODE|DATA} from KASLR's choice Chao Fan <fanc.fnst@cn.fujitsu.com> - 2017-07-06 12:10 +0200
Re: [PATCH] x86/boot/KASLR: exclude EFI_BOOT_SERVICES_{CODE|DATA} from KASLR's choice Chao Fan <fanc.fnst@cn.fujitsu.com> - 2017-07-06 12:30 +0200
Re: [PATCH] x86/boot/KASLR: exclude EFI_BOOT_SERVICES_{CODE|DATA} from KASLR's choice Matt Fleming <matt@codeblueprint.co.uk> - 2017-07-06 17:00 +0200
Re: [PATCH] x86/boot/KASLR: exclude EFI_BOOT_SERVICES_{CODE|DATA} from KASLR's choice Baoquan He <bhe@redhat.com> - 2017-07-07 05:10 +0200
Re: [PATCH] x86/boot/KASLR: exclude EFI_BOOT_SERVICES_{CODE|DATA} from KASLR's choice Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2017-07-07 08:20 +0200
Re: [PATCH] x86/boot/KASLR: exclude EFI_BOOT_SERVICES_{CODE|DATA} from KASLR's choice Matt Fleming <matt@codeblueprint.co.uk> - 2017-07-07 13:00 +0200
Re: [PATCH] x86/boot/KASLR: exclude EFI_BOOT_SERVICES_{CODE|DATA} from KASLR's choice Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2017-07-10 07:50 +0200
[PATCH v3 2/2] x86/efi: clean up dead code around efi_reserve_boot_services() Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2017-07-10 08:00 +0200
[PATCH v3 1/2] x86/boot/KASLR: exclude EFI_BOOT_SERVICES_{CODE|DATA} from KASLR's choice Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2017-07-10 08:00 +0200
Re: [PATCH] x86/boot/KASLR: exclude EFI_BOOT_SERVICES_{CODE|DATA} from KASLR's choice Matt Fleming <matt@codeblueprint.co.uk> - 2017-07-07 13:00 +0200
Re: [PATCH] x86/boot/KASLR: exclude EFI_BOOT_SERVICES_{CODE|DATA} from KASLR's choice Baoquan He <bhe@redhat.com> - 2017-07-09 12:50 +0200
Re: [PATCH] x86/boot/KASLR: exclude EFI_BOOT_SERVICES_{CODE|DATA} from KASLR's choice Baoquan He <bhe@redhat.com> - 2017-07-09 16:30 +0200
[PATCH v2 2/2] x86/efi: clean up dead code around efi_reserve_boot_services() Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2017-07-07 09:30 +0200
[PATCH v2 1/2] x86/boot/KASLR: exclude EFI_BOOT_SERVICES_{CODE|DATA} from KASLR's choice Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2017-07-07 09:30 +0200
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