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ext3: Fix an overflow in ext3_trim_fs.

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In a bs=4096 volume, if we call FITRIM with the following parameter as
fstrim_range(start = 102400, len = 134144000, minlen = 10240), with the
following code:
if (len >= EXT3_BLOCKS_PER_GROUP(sb))
        len -= (EXT3_BLOCKS_PER_GROUP(sb) - first_block);
else
        last_block = first_block + len;

So if len < EXT3_BLOCKS_PER_GROUP while first_block + len >
EXT3_BLOCKS_PER_GROUP, last_block will be set to an overflow value
which exceeds EXT3_BLOCKS_PER_GROUP.

This patch fixes it and adjusts len and last_block accordingly.

Cc: Lukas Czerner <lczerner@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Tao Ma 2011-03-03 22:58:37 +08:00 committed by Jan Kara
parent 3c26bdb423
commit 425fa41072
1 changed files with 8 additions and 3 deletions
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11
fs/ext3/balloc.c
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@ -2127,10 +2127,15 @@ int ext3_trim_fs(struct super_block *sb, struct fstrim_range *range)
if (free_blocks < minlen)
continue;
if (len >= EXT3_BLOCKS_PER_GROUP(sb))
len -= (EXT3_BLOCKS_PER_GROUP(sb) - first_block);
else
/*
* For all the groups except the last one, last block will
* always be EXT3_BLOCKS_PER_GROUP(sb), so we only need to
* change it for the last group in which case first_block +
* len < EXT3_BLOCKS_PER_GROUP(sb).
*/
if (first_block + len < EXT3_BLOCKS_PER_GROUP(sb))
last_block = first_block + len;
len -= last_block - first_block;
ret = ext3_trim_all_free(sb, group, first_block,
last_block, minlen);