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Subject[PATCH v3] partitions/efi: Fix partition name parsing in GUID partition entry
Date
GUID partition entry defined to have a partition name as 36 UTF-16LE
code units. This means that on big-endian platforms ASCII symbols
would be read with 0xXX00 efi_char16_t character code. In order to
correctly extract ASCII characters from a partition name field we
should be converted from 16LE to CPU architecture.

The problem exists on all big endian platforms.

Signed-off-by: Nikolai Merinov <n.merinov@inango-systems.com>
---
block/partitions/efi.c | 3 ++-
block/partitions/efi.h | 2 +-
include/linux/efi.h | 5 +++++
3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/block/partitions/efi.c b/block/partitions/efi.c
index db2fef7dfc47..f1d0820de844 100644
--- a/block/partitions/efi.c
+++ b/block/partitions/efi.c
@@ -715,7 +715,8 @@ int efi_partition(struct parsed_partitions *state)
ARRAY_SIZE(ptes[i].partition_name));
info->volname[label_max] = 0;
while (label_count < label_max) {
- u8 c = ptes[i].partition_name[label_count] & 0xff;
+ u8 c = 0xff & efi_char16le_to_cpu(
+ ptes[i].partition_name[label_count]);
if (c && !isprint(c))
c = '!';
info->volname[label_count] = c;
diff --git a/block/partitions/efi.h b/block/partitions/efi.h
index 3e8576157575..4d4cae0bb79e 100644
--- a/block/partitions/efi.h
+++ b/block/partitions/efi.h
@@ -88,7 +88,7 @@ typedef struct _gpt_entry {
__le64 starting_lba;
__le64 ending_lba;
gpt_entry_attributes attributes;
- efi_char16_t partition_name[72 / sizeof (efi_char16_t)];
+ efi_char16le_t partition_name[72 / sizeof(efi_char16le_t)];
} __packed gpt_entry;

typedef struct _gpt_mbr_record {
diff --git a/include/linux/efi.h b/include/linux/efi.h
index aa54586db7a5..47882f2d45db 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -45,9 +45,14 @@
typedef unsigned long efi_status_t;
typedef u8 efi_bool_t;
typedef u16 efi_char16_t; /* UNICODE character */
+typedef __le16 efi_char16le_t; /* UTF16-LE */
+typedef __be16 efi_char16be_t; /* UTF16-BE */
typedef u64 efi_physical_addr_t;
typedef void *efi_handle_t;

+#define efi_char16le_to_cpu le16_to_cpu
+#define efi_char16be_to_cpu be16_to_cpu
+
/*
* The UEFI spec and EDK2 reference implementation both define EFI_GUID as
* struct { u32 a; u16; b; u16 c; u8 d[8]; }; and so the implied alignment
--
2.17.1
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