Re: [PATCH 3/4] acpi: fix OEM ID/OEM Table ID padding

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Jan 12, 2022 at 08:46:16PM +0530, Ani Sinha wrote:
> 
> 
> On Wed, 12 Jan 2022, Michael S. Tsirkin wrote:
> 
> > On Wed, Jan 12, 2022 at 08:03:31AM -0500, Igor Mammedov wrote:
> > > Commit [2] broke original '\0' padding of OEM ID and OEM Table ID
> > > fields in headers of ACPI tables. While it doesn't have impact on
> > > default values since QEMU uses 6 and 8 characters long values
> > > respectively, it broke usecase where IDs are provided on QEMU CLI.
> > > It shouldn't affect guest (but may cause licensing verification
> > > issues in guest OS).
> > > One of the broken usecases is user supplied SLIC table with IDs
> > > shorter than max possible length, where [2] mangles IDs with extra
> > > spaces in RSDT and FADT tables whereas guest OS expects those to
> > > mirror the respective values of the used SLIC table.
> > >
> > > Fix it by replacing whitespace padding with '\0' padding in
> > > accordance with [1] and expectations of guest OS
> > >
> > > 1) ACPI spec, v2.0b
> > >        17.2 AML Grammar Definition
> > >        ...
> > >        //OEM ID of up to 6 characters. If the OEM ID is
> > >        //shorter than 6 characters, it can be terminated
> > >        //with a NULL character.
> > >
> > > 2)
> > > Fixes: 602b458201 ("acpi: Permit OEM ID and OEM table ID fields to be changed")
> >
> >
> > and add:
> >
> > Fixes: https://gitlab.com/qemu-project/qemu/-/issues/707
> 
> He did that already with the "Resolves:" line below.

oh sorry

> >
> > ?
> >
> > > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/707
> > > Reported-by: Dmitry V. Orekhov <dima.orekhov@gmail.com>
> > > Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> > > Cc: qemu-stable@nongnu.org
> > > ---
> > >  hw/acpi/aml-build.c | 4 ++--
> > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/hw/acpi/aml-build.c b/hw/acpi/aml-build.c
> > > index b3b3310df3..65148d5b9d 100644
> > > --- a/hw/acpi/aml-build.c
> > > +++ b/hw/acpi/aml-build.c
> > > @@ -1724,9 +1724,9 @@ void acpi_table_begin(AcpiTable *desc, GArray *array)
> > >      build_append_int_noprefix(array, 0, 4); /* Length */
> > >      build_append_int_noprefix(array, desc->rev, 1); /* Revision */
> > >      build_append_int_noprefix(array, 0, 1); /* Checksum */
> > > -    build_append_padded_str(array, desc->oem_id, 6, ' '); /* OEMID */
> > > +    build_append_padded_str(array, desc->oem_id, 6, '\0'); /* OEMID */
> > >      /* OEM Table ID */
> > > -    build_append_padded_str(array, desc->oem_table_id, 8, ' ');
> > > +    build_append_padded_str(array, desc->oem_table_id, 8, '\0');
> > >      build_append_int_noprefix(array, 1, 4); /* OEM Revision */
> > >      g_array_append_vals(array, ACPI_BUILD_APPNAME8, 4); /* Creator ID */
> > >      build_append_int_noprefix(array, 1, 4); /* Creator Revision */
> > > --
> > > 2.31.1
> >
> >