[PATCH 2/8] partitions/efi: check pmbr record's starting lba

[Davidlohr Bueso]

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.

Signed-off-by: Davidlohr Bueso <davidlohr@xxxxxx>
---
 block/partitions/efi.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/block/partitions/efi.c b/block/partitions/efi.c
index 3ebd3d8..6a997b1 100644
--- a/block/partitions/efi.c
+++ b/block/partitions/efi.c
@@ -151,9 +151,18 @@ static u64 last_lba(struct block_device *bdev)
 
 static inline int pmbr_part_valid(gpt_record *part)
 {
-        if (part->os_type == EFI_PMBR_OSTYPE_EFI_GPT &&
-            le32_to_cpu(part->start_sector) == 1UL)
-                return 1;
+        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;
 }
 
-- 
1.7.11.7

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