[PATCH 3.10 20/24] ext2: Fix oops in ext2_get_block() called from ext2_quota_write()

From: Greg Kroah-Hartman
Date: Sun Dec 14 2014 - 15:51:38 EST

3.10-stable review patch. If anyone has any objections, please let me know.


From: Jan Kara <jack@xxxxxxx>

commit df4e7ac0bb70abc97fbfd9ef09671fc084b3f9db upstream.

ext2_quota_write() doesn't properly setup bh it passes to
ext2_get_block() and thus we hit assertion BUG_ON(maxblocks == 0) in
ext2_get_blocks() (or we could actually ask for mapping arbitrary number
of blocks depending on whatever value was on stack).

Fix ext2_quota_write() to properly fill in number of blocks to map.

Reviewed-by: "Theodore Ts'o" <tytso@xxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Reported-by: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

fs/ext2/super.c | 1 +
1 file changed, 1 insertion(+)

--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -1493,6 +1493,7 @@ static ssize_t ext2_quota_write(struct s
sb->s_blocksize - offset : towrite;

tmp_bh.b_state = 0;
+ tmp_bh.b_size = sb->s_blocksize;
err = ext2_get_block(inode, blk, &tmp_bh, 1);
if (err < 0)
goto out;

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