A NULL pointer dereference issue was found in ksmbd, a high-performance in-kernel SMB server. Quoting ZDI security advisory [1]:

"This vulnerability allows remote attackers to create a denial-of-service condition on affected installations of Linux Kernel. Authentication is not required to exploit this vulnerability, but only systems with ksmbd enabled are vulnerable.

The specific flaw exists within the handling of SMB2_TREE_CONNECT and SMB2_QUERY_INFO commands. The issue results from the lack of proper validation of a pointer prior to accessing it. An attacker can leverage this vulnerability to create a denial-of-service condition on the system."

[1] https://www.zerodayinitiative.com/advisories/ZDI-CAN-20479/