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

[Paul Menzel]

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@xxxxxxxxxxxxx>
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Joerg Roedel <joro@xxxxxxxxxx>
> Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> ---
>   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@xxxxxxxxxxxxx>

Should this be tagged for the stable series?


Kind regards,

Paul