btrfs: free btrfs_path before copying inodes to userspace

btrfs_ioctl_logical_to_ino() frees the search path after the userspace
copy from the temp buffer @inodes. Which potentially can lead to a lock
splat.

Fix this by freeing the path before we copy @inodes to userspace.

CC: stable@vger.kernel.org # 4.19+
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 89b8d14..b595f2c 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -4282,21 +4282,20 @@ static long btrfs_ioctl_logical_to_ino(struct btrfs_fs_info *fs_info,
                size = min_t(u32, loi->size, SZ_16M);
        }
 
-       path = btrfs_alloc_path();
-       if (!path) {
-               ret = -ENOMEM;
-               goto out;
-       }
-
        inodes = init_data_container(size);
        if (IS_ERR(inodes)) {
                ret = PTR_ERR(inodes);
-               inodes = NULL;
-               goto out;
+               goto out_loi;
        }
 
+       path = btrfs_alloc_path();
+       if (!path) {
+               ret = -ENOMEM;
+               goto out;
+       }
        ret = iterate_inodes_from_logical(loi->logical, fs_info, path,
                                          inodes, ignore_offset);
+       btrfs_free_path(path);
        if (ret == -EINVAL)
                ret = -ENOENT;
        if (ret < 0)
@@ -4308,7 +4307,6 @@ static long btrfs_ioctl_logical_to_ino(struct btrfs_fs_info *fs_info,
                ret = -EFAULT;
 
 out:
-       btrfs_free_path(path);
        kvfree(inodes);
 out_loi:
        kfree(loi);