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ext4: fix overflow caused by missing cast in ext4_resize_fs() 

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: 1c6bd7173d
Signed-off-by: Jerry Lee <jerrylee@qnap.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org # 3.7+
This commit is contained in:
Jerry Lee 2017-08-06 01:18:31 -04:00 committed by Theodore Ts'o
parent c03b45b853
commit aec51758ce
1 changed files with 2 additions and 1 deletions
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3
fs/ext4/resize.c
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@ -1927,7 +1927,8 @@ int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t n_blocks_count)
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 */
}