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Subject[PATCH v4] efi: take size of partition entry from GPT header
Use gpt_header.sizeof_partition_entry instead of sizeof(gpt_entry)
for GPT entry size.
According to UEFI 2.7 spec 5.3.1 "GPT overview":, the size of a GUID Partition
Entry element is defined in the Size Of Partition Entry field of GPT header.
The GPT with entries sized more than sizeof(gpt_entry) is not illegal.
OVMF firmware from EDK2 perfectly works with it, see edk2-tianocore source
code.

Changes since v1: refactoring (extract get_gpt_entry function),
fix (&ptes[i] -> pte)
Changes since v2: use le32_to_cpu, fix typo, sanity check for
sizeof_partition_entry
Changes since v3: style fixes

Signed-off-by: Eugene Korenevsky <ekorenevsky@gmail.com>
---
block/partitions/efi.c | 31 ++++++++++++++++++++-----------
1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/block/partitions/efi.c b/block/partitions/efi.c
index 39f70d968754..0d10a582b5bc 100644
--- a/block/partitions/efi.c
+++ b/block/partitions/efi.c
@@ -429,8 +429,8 @@ static int is_gpt_valid(struct parsed_partitions *state, u64 lba,
goto fail;
}
/* Check that sizeof_partition_entry has the correct value */
- if (le32_to_cpu((*gpt)->sizeof_partition_entry) != sizeof(gpt_entry)) {
- pr_debug("GUID Partition Entry Size check failed.\n");
+ if (le32_to_cpu((*gpt)->sizeof_partition_entry) < sizeof(gpt_entry)) {
+ pr_debug("GUID Partition Entry Size is too small.\n");
goto fail;
}

@@ -670,6 +670,12 @@ static int find_valid_gpt(struct parsed_partitions *state, gpt_header **gpt,
return 0;
}

+static gpt_entry *get_gpt_entry(gpt_header *gpt, gpt_entry *ptes, u32 index)
+{
+ return (gpt_entry *)((u8 *)ptes +
+ le32_to_cpu(gpt->sizeof_partition_entry) * index);
+}
+
/**
* efi_partition(struct parsed_partitions *state)
* @state: disk parsed partitions
@@ -704,32 +710,35 @@ int efi_partition(struct parsed_partitions *state)

pr_debug("GUID Partition Table is valid! Yea!\n");

- for (i = 0; i < le32_to_cpu(gpt->num_partition_entries) && i < state->limit-1; i++) {
+ for (i = 0; i < le32_to_cpu(gpt->num_partition_entries) &&
+ i < state->limit-1; i++) {
+ gpt_entry *pte = get_gpt_entry(gpt, ptes, i);
struct partition_meta_info *info;
unsigned label_count = 0;
unsigned label_max;
- u64 start = le64_to_cpu(ptes[i].starting_lba);
- u64 size = le64_to_cpu(ptes[i].ending_lba) -
- le64_to_cpu(ptes[i].starting_lba) + 1ULL;
+ u64 start = le64_to_cpu(pte->starting_lba);
+ u64 size = le64_to_cpu(pte->ending_lba) -
+ le64_to_cpu(pte->starting_lba) + 1ULL;

- if (!is_pte_valid(&ptes[i], last_lba(state->bdev)))
+ if (!is_pte_valid(pte, last_lba(state->bdev)))
continue;

put_partition(state, i+1, start * ssz, size * ssz);

/* If this is a RAID volume, tell md */
- if (!efi_guidcmp(ptes[i].partition_type_guid, PARTITION_LINUX_RAID_GUID))
+ if (!efi_guidcmp(pte->partition_type_guid,
+ PARTITION_LINUX_RAID_GUID))
state->parts[i + 1].flags = ADDPART_FLAG_RAID;

info = &state->parts[i + 1].info;
- efi_guid_to_str(&ptes[i].unique_partition_guid, info->uuid);
+ efi_guid_to_str(&pte->unique_partition_guid, info->uuid);

/* Naively convert UTF16-LE to 7 bits. */
label_max = min(ARRAY_SIZE(info->volname) - 1,
- ARRAY_SIZE(ptes[i].partition_name));
+ ARRAY_SIZE(pte->partition_name));
info->volname[label_max] = 0;
while (label_count < label_max) {
- u8 c = ptes[i].partition_name[label_count] & 0xff;
+ u8 c = pte->partition_name[label_count] & 0xff;
if (c && !isprint(c))
c = '!';
info->volname[label_count] = c;
--
2.18.0
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