linux-kernel - Re: [PATCH v2] partitions/efi: Fix partition name parsing in GUID partition entry

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Date:   Tue, 24 Dec 2019 10:51:19 +0100
From:   Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:     Nikolai Merinov <n.merinov@...ngo-systems.com>
Cc:     Davidlohr Bueso <dave@...olabs.net>, Jens Axboe <axboe@...nel.dk>,
        linux-efi <linux-efi@...r.kernel.org>,
        linux-block@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] partitions/efi: Fix partition name parsing in GUID
 partition entry

On Tue, 24 Dec 2019 at 10:29, Nikolai Merinov
<n.merinov@...ngo-systems.com> wrote:
>
> 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@...ngo-systems.com>
>

Acked-by: Ard Biesheuvel <ardb@...nel.org>

> diff --git a/block/partitions/efi.c b/block/partitions/efi.c
> index db2fef7dfc47..51287a8a3bea 100644
> --- a/block/partitions/efi.c
> +++ b/block/partitions/efi.c
> @@ -715,7 +715,7 @@ 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 = le16_to_cpu(ptes[i].partition_name[label_count]) & 0xff;
>                         if (c && !isprint(c))
>                                 c = '!';
>                         info->volname[label_count] = c;
> diff --git a/block/partitions/efi.h b/block/partitions/efi.h
> index 3e8576157575..0b6d5b7be111 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)];
> +       __le16 partition_name[72 / sizeof (__le16)];
>  } __packed gpt_entry;
>
>  typedef struct _gpt_mbr_record {
> --
> 2.17.1
>