From 425fa41072b7dce3d88f392b335e561a770aa6c3 Mon Sep 17 00:00:00 2001
From: Tao Ma <boyu.mt@taobao.com>
Date: Thu, 3 Mar 2011 22:58:37 +0800
Subject: ext3: Fix an overflow in ext3_trim_fs.
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>
---
fs/ext3/balloc.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
(limited to 'fs/ext3/balloc.c')
diff --git a/fs/ext3/balloc.c b/fs/ext3/balloc.c
index db1906b4e39c..153242187fce 100644
--- a/fs/ext3/balloc.c
+++ b/fs/ext3/balloc.c
@@ -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);
--
cgit