In the Linux kernel, the following vulnerability has been resolved:
af_unix: Reject SIOCATMARK on non-stream sockets
SIOCATMARK reports whether the receive queue is at the urgent mark for MSG_OOB.
In AFUNIX, MSGOOB is supported only for SOCKSTREAM sockets. SOCKDGRAM and SOCKSEQPACKET reject MSGOOB in sendmsg() and recvmsg(), so they should not support SIOCATMARK either.
Return -EOPNOTSUPP for non-stream sockets before checking the receive queue.