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ext4: Fix a double free of sbi->s_group_info in ext4_mb_init_backend

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If we meet with an error in ext4_mb_add_groupinfo, we kfree
sbi->s_group_info[group >> EXT4_DESC_PER_BLOCK_BITS(sb)], but fail to
reset it to NULL. So the caller ext4_mb_init_backend will try to kfree
it again and causes a double free. So fix it by resetting it to NULL.

Some typo in comments of mballoc.c are also changed.

Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Tao Ma 2011-07-11 18:42:42 -04:00 committed by Theodore Ts'o
parent 823ba01fc0
commit caaf7a29d3
1 changed files with 7 additions and 5 deletions
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12
fs/ext4/mballoc.c
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@ -75,8 +75,8 @@
*
* The inode preallocation space is used looking at the _logical_ start
* block. If only the logical file block falls within the range of prealloc
* space we will consume the particular prealloc space. This make sure that
* that the we have contiguous physical blocks representing the file blocks
* space we will consume the particular prealloc space. This makes sure that
* we have contiguous physical blocks representing the file blocks
*
* The important thing to be noted in case of inode prealloc space is that
* we don't modify the values associated to inode prealloc space except
@ -84,7 +84,7 @@
*
* If we are not able to find blocks in the inode prealloc space and if we
* have the group allocation flag set then we look at the locality group
* prealloc space. These are per CPU prealloc list repreasented as
* prealloc space. These are per CPU prealloc list represented as
*
* ext4_sb_info.s_locality_groups[smp_processor_id()]
*
@ -152,7 +152,7 @@
* best extent in the found extents. Searching for the blocks starts with
* the group specified as the goal value in allocation context via
* ac_g_ex. Each group is first checked based on the criteria whether it
* can used for allocation. ext4_mb_good_group explains how the groups are
* can be used for allocation. ext4_mb_good_group explains how the groups are
* checked.
*
* Both the prealloc space are getting populated as above. So for the first
@ -2279,8 +2279,10 @@ int ext4_mb_add_groupinfo(struct super_block *sb, ext4_group_t group,
exit_group_info:
/* If a meta_group_info table has been allocated, release it now */
if (group % EXT4_DESC_PER_BLOCK(sb) == 0)
if (group % EXT4_DESC_PER_BLOCK(sb) == 0) {
kfree(sbi->s_group_info[group >> EXT4_DESC_PER_BLOCK_BITS(sb)]);
sbi->s_group_info[group >> EXT4_DESC_PER_BLOCK_BITS(sb)] = NULL;
}
exit_meta_group_info:
return -ENOMEM;
} /* ext4_mb_add_groupinfo */