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    Subject[PATCH 3.16 096/294] ext4: fix overflow caused by missing cast in ext4_resize_fs()
    3.16.50-rc1 review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Jerry Lee <jerrylee@qnap.com>

    commit aec51758ce10a9c847a62a48a168f8c804c6e053 upstream.

    On a 32-bit platform, the value of n_blcoks_count may be wrong during
    the file system is resized to size larger than 2^32 blocks. This may
    caused the superblock being corrupted with zero blocks count.

    Fixes: 1c6bd7173d66
    Signed-off-by: Jerry Lee <jerrylee@qnap.com>
    Signed-off-by: Theodore Ts'o <tytso@mit.edu>
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    fs/ext4/resize.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    --- a/fs/ext4/resize.c
    +++ b/fs/ext4/resize.c
    @@ -1929,7 +1929,8 @@ retry:
    n_desc_blocks = o_desc_blocks +
    le16_to_cpu(es->s_reserved_gdt_blocks);
    n_group = n_desc_blocks * EXT4_DESC_PER_BLOCK(sb);
    - n_blocks_count = n_group * EXT4_BLOCKS_PER_GROUP(sb);
    + n_blocks_count = (ext4_fsblk_t)n_group *
    + EXT4_BLOCKS_PER_GROUP(sb);
    n_group--; /* set to last group number */
    }

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