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hw/i386: Replace magic number with field length calculation

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Replce the literal magic number 48 with length calculation (32 bytes at
the end of the firmware after the table footer + 16 bytes of the OVMF
table footer GUID).

No functional change intended.

Signed-off-by: Dov Murik <dovmurik@linux.ibm.com>
Message-Id: <20220222071906.2632426-3-dovmurik@linux.ibm.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
This commit is contained in:
Dov Murik 2022-02-22 07:19:06 +00:00 committed by Michael S. Tsirkin
parent e5aaeac355
commit 9919423516
1 changed files with 6 additions and 3 deletions
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9
hw/i386/pc_sysfw_ovmf.c
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@ -30,6 +30,8 @@
#define OVMF_TABLE_FOOTER_GUID "96b582de-1fb2-45f7-baea-a366c55a082d"
static const int bytes_after_table_footer = 32;
static bool ovmf_flash_parsed;
static uint8_t *ovmf_table;
static int ovmf_table_len;
@ -53,12 +55,13 @@ void pc_system_parse_ovmf_flash(uint8_t *flash_ptr, size_t flash_size)
/*
* if this is OVMF there will be a table footer
* guid 48 bytes before the end of the flash file. If it's
* not found, silently abort the flash parsing.
* guid 48 bytes before the end of the flash file
* (= 32 bytes after the table + 16 bytes the GUID itself).
* If it's not found, silently abort the flash parsing.
*/
qemu_uuid_parse(OVMF_TABLE_FOOTER_GUID, &guid);
guid = qemu_uuid_bswap(guid); /* guids are LE */
ptr = flash_ptr + flash_size - 48;
ptr = flash_ptr + flash_size - (bytes_after_table_footer + sizeof(guid));
if (!qemu_uuid_is_equal((QemuUUID *)ptr, &guid)) {
return;
}