target/linux/generic/pending-4.14/510-f2fs-fix-sanity_check_raw_super-on-big-endian-machines.patch

   1 From: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
   2 To: linux-f2fs-devel@lists.sourceforge.net, yuchao0@huawei.com,
   3         jaegeuk@kernel.org
   4 Subject: [PATCH v2 1/1] f2fs: fix validation of the block count in
   5  sanity_check_raw_super
   6 Date: Sat, 22 Dec 2018 11:22:26 +0100
   7 Message-Id: <20181222102226.10050-2-martin.blumenstingl@googlemail.com>
   8
   9 Treat "block_count" from struct f2fs_super_block as 64-bit little endian
  10 value in sanity_check_raw_super() because struct f2fs_super_block
  11 declares "block_count" as "__le64".
  12
  13 This fixes a bug where the superblock validation fails on big endian
  14 devices with the following error:
  15   F2FS-fs (sda1): Wrong segment_count / block_count (61439 > 0)
  16   F2FS-fs (sda1): Can't find valid F2FS filesystem in 1th superblock
  17   F2FS-fs (sda1): Wrong segment_count / block_count (61439 > 0)
  18   F2FS-fs (sda1): Can't find valid F2FS filesystem in 2th superblock
  19 As result of this the partition cannot be mounted.
  20
  21 With this patch applied the superblock validation works fine and the
  22 partition can be mounted again:
  23   F2FS-fs (sda1): Mounted with checkpoint version = 7c84
  24
  25 My little endian x86-64 hardware was able to mount the partition without
  26 this fix.
  27 To confirm that mounting f2fs filesystems works on big endian machines
  28 again I tested this on a 32-bit MIPS big endian (lantiq) device.
  29
  30 Fixes: 0cfe75c5b01199 ("f2fs: enhance sanity_check_raw_super() to avoid potential overflows")
  31 Cc: stable@vger.kernel.org
  32 Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
  33 Reviewed-by: Chao Yu <yuchao0@huawei.com>
  34 ---
  35
  36 --- a/fs/f2fs/super.c
  37 +++ b/fs/f2fs/super.c
  38 @@ -1897,10 +1897,10 @@ static int sanity_check_raw_super(struct
  39                 return 1;
  40         }
  41
  42 -       if (segment_count > (le32_to_cpu(raw_super->block_count) >> 9)) {
  43 +       if (segment_count > (le64_to_cpu(raw_super->block_count) >> 9)) {
  44                 f2fs_msg(sb, KERN_INFO,
  45 -                       "Wrong segment_count / block_count (%u > %u)",
  46 -                       segment_count, le32_to_cpu(raw_super->block_count));
  47 +                       "Wrong segment_count / block_count (%u > %llu)",
  48 +                       segment_count, le64_to_cpu(raw_super->block_count));
  49                 return 1;
  50         }
  51