On updating kernel versions (as below) and trying to mount CIFS shares from Synology (where Aggregation Portal is enabled) results in "mount error(40): Too many levels of symbolic links".

  • 5.3.18-150300.59.76 => 5.3.18-150300.59.87 (+)
  • 5.14.21-150400.22 => 5.14.21-150400.24.11 (+)

Disabling Aggregation Portal allows the mount to succeed.

I raised a case with Synology and they have said this is a SUSE Kernel issue.

When your client device sends a create request with DFS operation enabled, file path will ends up with \0, which will cause a mismatch with the Blob Length after the \0 has been ignored, and leads to a OBJECT_NAME_INVALID / Too many levels of symbolic links error.

We have also reproduce the issue with original samba 4.15.9 package as a SMB server. And the mount.cifs version will have different behaviors between under DFS and non-DFS operation (no extra \0 under non-DFS operation), and that is why the issue disappears after MSDFS option is disabled.