linux-kernel - Re: [PATCH] x86/mm, efi: Check for valid image type

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]

Message-ID: <20150729093752.GF31695@dhcp-128-89.nay.redhat.com>
Date:	Wed, 29 Jul 2015 17:37:52 +0800
From:	Dave Young <dyoung@...hat.com>
To:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:	josh@...htriplett.org, Matt Fleming <matt@...eblueprint.co.uk>,
	Matt Fleming <matt.fleming@...el.com>, x86@...nel.org,
	linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/mm, efi: Check for valid image type

Hi,

> 
> >  As you pointed out above, a wild pointer could cause a
> > WARN from early_ioremap.  We need to never follow the pointer in the
> > first place after a kexec, unless we have some way to know that it's
> > actually valid.
> 
> So you assume that the information from ACPI is always correct then?
> The pointer is correct, the information it points to is no longer.
> 
> If we run always under EFI then it looks like the variable efi_setup
> which is checked in efi_enter_virtual_mode() is 0 during normal boot
> and != 0 on kexec entry. This hint is set via setup_data / SETUP_EFI
> since commit 1fec053369 ("x86/efi: Pass necessary EFI data for kexec
> via setup_data"). So maybe we could use this to check if we run under
> kexec or not.

Not sure if BGRT is useful in kexec kernel, it seems not worth to copy
it between kernels.

IMO just return in case if (efi_setup) is true make sense.

Thanks
Dave
--
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/