Merge v6.18.19linux-rolling-lts

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 21 insertions, 3 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 736a1b317070..5f0bac5cea7e 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3984,6 +3984,25 @@ 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)
@@ -3999,8 +4018,6 @@ 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,
@@ -4022,7 +4039,8 @@ 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;
 	}