Re: [PATCH v3] partitions/efi: Fix partition name parsing in GUID partition entry

[Nikolai Merinov]

Hello,

Did you have a time to look at this patch? Should I make any modification? 

Regards,
Nikolai

----- Original Message -----
> From: "n merinov" <n.merinov@xxxxxxxxxxxxxxxxxx>
> To: hch@xxxxxxxxxxxxx, "Davidlohr Bueso" <dave@xxxxxxxxxxxx>, "Jens Axboe" <axboe@xxxxxxxxx>, "Ard Biesheuvel"
> <ardb@xxxxxxxxxx>, linux-efi@xxxxxxxxxxxxxxx, linux-block@xxxxxxxxxxxxxxx, "linux-kernel"
> <linux-kernel@xxxxxxxxxxxxxxx>
> Cc: "n merinov" <n.merinov@xxxxxxxxxxxxxxxxxx>
> Sent: Monday, January 13, 2020 3:27:23 PM
> Subject: [PATCH v3] partitions/efi: Fix partition name parsing in GUID partition entry

> 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@xxxxxxxxxxxxxxxxxx>
> ---
> 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