CVE-2026-31539: Concurrent Execution using Shared Resource with Improper Synchronization

In the Linux kernel, the following vulnerability has been resolved:

smb: smbdirect: introduce smbdirect_socket.recv_io.credits.available

The logic off managing recv credits by counting posted recv_io and granted credits is racy.

That's because the peer might already consumed a credit, but between receiving the incoming recv at the hardware and processing the completion in the 'recv_done' functions we likely have a window where we grant credits, which don't really exist.

So we better have a decicated counter for the available credits, which will be incremented when we posted new recv buffers and drained when we grant the credits to the peer.