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-rw-r--r--block/partitions/efi.c21
1 files changed, 18 insertions, 3 deletions
diff --git a/block/partitions/efi.c b/block/partitions/efi.c
index e3cb4f1..b028af6 100644
--- a/block/partitions/efi.c
+++ b/block/partitions/efi.c
@@ -166,6 +166,7 @@ invalid:
/**
* is_pmbr_valid(): test Protective MBR for validity
* @mbr: pointer to a legacy mbr structure
+ * @total_sectors: amount of sectors in the device
*
* Description: Checks for a valid protective or hybrid
* master boot record (MBR). The validity of a pMBR depends
@@ -180,9 +181,9 @@ invalid:
* Returns 0 upon invalid MBR, or GPT_MBR_PROTECTIVE or
* GPT_MBR_HYBRID depending on the device layout.
*/
-static int is_pmbr_valid(legacy_mbr *mbr)
+static int is_pmbr_valid(legacy_mbr *mbr, sector_t total_sectors)
{
- int i, ret = 0; /* invalid by default */
+ int i, part = 0, ret = 0; /* invalid by default */
if (!mbr || le16_to_cpu(mbr->signature) != MSDOS_MBR_SIGNATURE)
goto done;
@@ -190,6 +191,7 @@ static int is_pmbr_valid(legacy_mbr *mbr)
for (i = 0; i < 4; i++) {
ret = pmbr_part_valid(&mbr->partition_record[i]);
if (ret == GPT_MBR_PROTECTIVE) {
+ part = i;
/*
* Ok, we at least know that there's a protective MBR,
* now check if there are other partition types for
@@ -207,6 +209,18 @@ check_hybrid:
EFI_PMBR_OSTYPE_EFI_GPT) &&
(mbr->partition_record[i].os_type != 0x00))
ret = GPT_MBR_HYBRID;
+
+ /*
+ * Protective MBRs take up the lesser of the whole disk
+ * or 2 TiB (32bit LBA), ignoring the rest of the disk.
+ *
+ * Hybrid MBRs do not necessarily comply with this.
+ */
+ if (ret == GPT_MBR_PROTECTIVE) {
+ if (le32_to_cpu(mbr->partition_record[part].size_in_lba) !=
+ min((uint32_t) total_sectors - 1, 0xFFFFFFFF))
+ ret = 0;
+ }
done:
return ret;
}
@@ -568,6 +582,7 @@ static int find_valid_gpt(struct parsed_partitions *state, gpt_header **gpt,
gpt_header *pgpt = NULL, *agpt = NULL;
gpt_entry *pptes = NULL, *aptes = NULL;
legacy_mbr *legacymbr;
+ sector_t total_sectors = i_size_read(state->bdev->bd_inode) >> 9;
u64 lastlba;
if (!ptes)
@@ -581,7 +596,7 @@ static int find_valid_gpt(struct parsed_partitions *state, gpt_header **gpt,
goto fail;
read_lba(state, 0, (u8 *)legacymbr, sizeof(*legacymbr));
- good_pmbr = is_pmbr_valid(legacymbr);
+ good_pmbr = is_pmbr_valid(legacymbr, total_sectors);
kfree(legacymbr);
if (!good_pmbr)
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