1 files changed, 37 insertions, 7 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index a1fd44c44ecf..d75d31b606e4 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -672,6 +672,13 @@ static noinline int create_subvol(struct mnt_idmap *idmap,
 		goto out;
 	}
 
+	/*
+	 * Subvolumes have orphans cleaned on first dentry lookup. A new
+	 * subvolume cannot have any orphans, so we should set the bit before we
+	 * add the subvolume dentry to the dentry cache, so that it is in the
+	 * same state as a subvolume after first lookup.
+	 */
+	set_bit(BTRFS_ROOT_ORPHAN_CLEANUP, &new_root->state);
 	d_instantiate_new(dentry, new_inode_args.inode);
 	new_inode_args.inode = NULL;
 
@@ -3610,7 +3617,8 @@ static long btrfs_ioctl_qgroup_assign(struct file *file, void __user *arg)
 		}
 	}
 
-	trans = btrfs_join_transaction(root);
+	/* 2 BTRFS_QGROUP_RELATION_KEY items. */
+	trans = btrfs_start_transaction(root, 2);
 	if (IS_ERR(trans)) {
 		ret = PTR_ERR(trans);
 		goto out;
@@ -3682,7 +3690,11 @@ static long btrfs_ioctl_qgroup_create(struct file *file, void __user *arg)
 		goto out;
 	}
 
-	trans = btrfs_join_transaction(root);
+	/*
+	 * 1 BTRFS_QGROUP_INFO_KEY item.
+	 * 1 BTRFS_QGROUP_LIMIT_KEY item.
+	 */
+	trans = btrfs_start_transaction(root, 2);
 	if (IS_ERR(trans)) {
 		ret = PTR_ERR(trans);
 		goto out;
@@ -3731,7 +3743,8 @@ static long btrfs_ioctl_qgroup_limit(struct file *file, void __user *arg)
 		goto drop_write;
 	}
 
-	trans = btrfs_join_transaction(root);
+	/* 1 BTRFS_QGROUP_LIMIT_KEY item. */
+	trans = btrfs_start_transaction(root, 1);
 	if (IS_ERR(trans)) {
 		ret = PTR_ERR(trans);
 		goto out;
@@ -3852,6 +3865,25 @@ static long _btrfs_ioctl_set_received_subvol(struct file *file,
 		goto out;
 	}
 
+	received_uuid_changed = memcmp(root_item->received_uuid, sa->uuid,
+				       BTRFS_UUID_SIZE);
+
+	/*
+	 * Before we attempt to add the new received uuid, check if we have room
+	 * for it in case there's already an item. If the size of the existing
+	 * item plus this root's ID (u64) exceeds the maximum item size, we can
+	 * return here without the need to abort a transaction. If we don't do
+	 * this check, the btrfs_uuid_tree_add() call below would fail with
+	 * -EOVERFLOW and result in a transaction abort. Malicious users could
+	 * exploit this to turn the fs into RO mode.
+	 */
+	if (received_uuid_changed && !btrfs_is_empty_uuid(sa->uuid)) {
+		ret = btrfs_uuid_tree_check_overflow(fs_info, sa->uuid,
+						     BTRFS_UUID_KEY_RECEIVED_SUBVOL);
+		if (ret < 0)
+			goto out;
+	}
+
 	/*
 	 * 1 - root item
 	 * 2 - uuid items (received uuid + subvol uuid)
@@ -3867,15 +3899,12 @@ static long _btrfs_ioctl_set_received_subvol(struct file *file,
 	sa->rtime.sec = ct.tv_sec;
 	sa->rtime.nsec = ct.tv_nsec;
 
-	received_uuid_changed = memcmp(root_item->received_uuid, sa->uuid,
-				       BTRFS_UUID_SIZE);
 	if (received_uuid_changed &&
 	    !btrfs_is_empty_uuid(root_item->received_uuid)) {
 		ret = btrfs_uuid_tree_remove(trans, root_item->received_uuid,
 					  BTRFS_UUID_KEY_RECEIVED_SUBVOL,
 					  btrfs_root_id(root));
 		if (unlikely(ret && ret != -ENOENT)) {
-		        btrfs_abort_transaction(trans, ret);
 		        btrfs_end_transaction(trans);
 		        goto out;
 		}
@@ -3890,7 +3919,8 @@ static long _btrfs_ioctl_set_received_subvol(struct file *file,
 
 	ret = btrfs_update_root(trans, fs_info->tree_root,
 				&root->root_key, &root->root_item);
-	if (ret < 0) {
+	if (unlikely(ret < 0)) {
+		btrfs_abort_transaction(trans, ret);
 		btrfs_end_transaction(trans);
 		goto out;
 	}