Re: [Bugfix 2/2] x86/PCI/ACPI: Relax ACPI resource descriptor checks to work around BIOS bugs

Rafael J. Wysocki
2015-03-04T14:02:28Z

On Wednesday, March 04, 2015 04:47:12 PM Jiang Liu wrote:
> Some BIOSes report incorrect length for ACPI address space descriptors,
> so relax the checks to avoid regressions. This issue has appeared several
> times as:
> 3162b6f0c5e1 ("PNPACPI: truncate _CRS windows with _LEN > _MAX - _MIN + 1")
> d558b483d5a7 ("x86/PCI: truncate _CRS windows with _LEN > _MAX - _MIN + 1")
> f238b414a74a ("PNPACPI: compute Address Space length rather than using _LEN")
> 48728e077480 ("x86/PCI: compute Address Space length rather than using _LEN")
>
> Please refer to https://bugzilla.kernel.org/show_bug.cgi?id=94221
> for more details and example malformed ACPI resource descriptors.
>
> Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
> Tested-by: Dave Airlie <airlied@redhat.com>
> Tested-by: Prakash Punnoor <prakash@punnoor.de>

Queued up for 4.0-rc3, thanks!

Bjorn, please let me know if you have any objections.

> ---
> drivers/acpi/resource.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/acpi/resource.c b/drivers/acpi/resource.c
> index c723668e3e27..5589a6e2a023 100644
> --- a/drivers/acpi/resource.c
> +++ b/drivers/acpi/resource.c
> @@ -42,8 +42,10 @@ static bool acpi_dev_resource_len_valid(u64 start, u64 end, u64 len, bool io)
> * CHECKME: len might be required to check versus a minimum
> * length as well. 1 for io is fine, but for memory it does
> * not make any sense at all.
> + * Note: some BIOSes report incorrect length for ACPI address space
> + * descriptor, so remove check of 'reslen == len' to avoid regression.
> */
> - if (len && reslen && reslen == len && start <= end)
> + if (len && reslen && start <= end)
> return true;
>
> pr_debug("ACPI: invalid or unassigned resource %s [%016llx - %016llx] length [%016llx]\n",
>

--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.