[PATCH 3.11 030/208] ext2: Fix oops in ext2_get_block() called from ext2_quota_write()

[Luis Henriques]

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

------------------

From: Jan Kara <jack at suse.cz>

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 at mit.edu>
Reviewed-by: Christoph Hellwig <hch at lst.de>
Reported-by: Christoph Hellwig <hch at infradead.org>
Signed-off-by: Jan Kara <jack at suse.cz>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 fs/ext2/super.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index 2885349..20d6697 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -1493,6 +1493,7 @@ static ssize_t ext2_quota_write(struct super_block *sb, int type,
 				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;
-- 
1.8.3.2