[PATCH 1/2] ocfs2: Refuse to enable ocfs2 format for another filesystem

[Jan Kara <jack@suse.cz>]

It is possible to issue Q_QUOTAON quotactl(2) e.g. for ext4 filesystem
requesting to enable quota using ocfs2 quota format. With suitable
passed arguments this can get upto ocfs2_local_check_quota_file() where
the passed superblock is from the ext4 filesystem and that can cause all
sorts of interesting things, most likely crashes. As ocfs2 quotas are
specific to ocfs2 filesystem, verify we are indeed enabling quotas
there.

Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ocfs2/quota_local.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/ocfs2/quota_local.c b/fs/ocfs2/quota_local.c
index f55810c59b1b..97dee8ee6096 100644
--- a/fs/ocfs2/quota_local.c
+++ b/fs/ocfs2/quota_local.c
@@ -171,6 +171,10 @@ static int ocfs2_local_check_quota_file(struct super_block *sb, int type)
 	struct ocfs2_disk_dqheader *dqhead;
 	int status, ret = 0;
 
+	/* OCFS2 quota format is supported only for OCFS2 filesystems */
+	if (strcmp(sb->s_type->name, "ocfs2"))
+		goto out_err;
+
 	/* First check whether we understand local quota file */
 	status = ocfs2_read_quota_block(linode, 0, &bh);
 	if (status) {
-- 
2.51.0