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acpi: fix OEM ID/OEM Table ID padding

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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")
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
Message-Id: <20220112130332.1648664-4-imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Ani Sinha <ani@anisinha.ca>
Tested-by: Dmitry V. Orekhov dima.orekhov@gmail.com
This commit is contained in:
Igor Mammedov 2022-01-12 08:03:31 -05:00 committed by Michael S. Tsirkin
parent d1e4a46541
commit 748c030f36
1 changed files with 2 additions and 2 deletions
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4
hw/acpi/aml-build.c
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@ -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 */