partitions/efi: check pmbr record's starting lba

Per the UEFI Specs 2.4, June 2013, the starting lba of the partition that
has the EFI GPT (0xEE) must be set to 0x00000001 - this is obviously the
LBA of the GPT Partition Header.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Reviewed-by: Karel Zak <kzak@redhat.com>
Acked-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 13 insertions, 4 deletions

diff --git a/block/partitions/efi.c b/block/partitions/efi.c
index bd8fb22b2109..7a2b74f0d06f 100644
--- a/block/partitions/efi.c
+++ b/block/partitions/efi.c
@@ -151,10 +151,19 @@ static u64 last_lba(struct block_device *bdev)
 
 static inline int pmbr_part_valid(gpt_mbr_record *part)
 {
-        if (part->os_type == EFI_PMBR_OSTYPE_EFI_GPT &&
-            le32_to_cpu(part->start_sector) == 1UL)
-                return 1;
-        return 0;
+        if (part->os_type != EFI_PMBR_OSTYPE_EFI_GPT)
+                goto invalid;
+
+        /* set to 0x00000001 (i.e., the LBA of the GPT Partition Header) */
+        if (le32_to_cpu(part->starting_lba) != GPT_PRIMARY_PARTITION_TABLE_LBA)
+                goto invalid;
+
+        if (le32_to_cpu(part->start_sector) != 1UL)
+                goto invalid;
+
+        return 1;
+invalid:
+        return 0;
 }
 
 /**