linux-kernel - Re: [PATCH] x86/mm: Do not warn about PCI BIOS W+X mappings

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] [day] [month] [year] [list]

Message-ID: <b1231b76-fd35-4304-8003-b2dccee1ba0d@molgen.mpg.de>
Date:   Fri, 12 Oct 2018 01:23:43 +0200
From:   Paul Menzel <pmenzel@...gen.mpg.de>
To:     Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, Joerg Roedel <joro@...tes.org>,
        Kees Cook <keescook@...omium.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH] x86/mm: Do not warn about PCI BIOS W+X mappings

Dear Thomas,


Am 08.10.2018 um 21:53 schrieb Thomas Gleixner:
> PCI BIOS requires the BIOS area 0x0A0000-0x0FFFFFF to be mapped W+X for
> various legacy reasons. When CONFIG_DEBUG_WX is enabled, this triggers the
> WX warning, but this is misleading because the mapping is required and is
> not a result of an accidental oversight.
> 
> Prevent the full warning when PCI BIOS is enabled and the detected WX
> mapping is in the BIOS area. Just emit a pr_warn() which denotes the
> fact. This is partially duplicating the info which the PCI BIOS code emits
> when it maps the area as executable, but that info is not in the context of
> the WX checking output.
> 
> Reported-by: Paul Menzel <pmenzel@...gen.mpg.de>
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Cc: Joerg Roedel <joro@...tes.org>
> Cc: Kees Cook <keescook@...omium.org>
> Cc: Bjorn Helgaas <bhelgaas@...gle.com>
> ---
>   arch/x86/mm/dump_pagetables.c |   35 +++++++++++++++++++++++++++--------
>   1 file changed, 27 insertions(+), 8 deletions(-)

Thank you for the patch. I tested it on the ASRock E350M1 with coreboot 
and the SeaBIOS payload, and the insecure warning is gone.

Tested-by: Paul Menzel <pmenzel@...gen.mpg.de>

Should this be tagged for the stable series?


Kind regards,

Paul