| From aec51758ce10a9c847a62a48a168f8c804c6e053 Mon Sep 17 00:00:00 2001 |
| From: Jerry Lee <jerrylee@qnap.com> |
| Date: Sun, 6 Aug 2017 01:18:31 -0400 |
| Subject: ext4: fix overflow caused by missing cast in ext4_resize_fs() |
| |
| 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| fs/ext4/resize.c | 3 ++- |
| 1 file changed, 2 insertions(+), 1 deletion(-) |
| |
| --- a/fs/ext4/resize.c |
| +++ b/fs/ext4/resize.c |
| @@ -1926,7 +1926,8 @@ 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 */ |
| } |
| |
