Linux kernel (net/tls): The thread in recvmsg/sendmsg can exit as soon as the async crypto callback signals completion

Impact

The thread in recvmsg/sendmsg can exit as soon as the async crypto callback signals completion, so everything the callback touches afterwards is already-freed socket and context memory. A peer that times its records against a closing socket gets a use-after-free on the node.

Who can reach it

Remote plus a local close: the peer supplies records to a kTLS socket while the owning process closes or returns from the syscall - a normal pattern for short-lived tenant connections, and one an attacker can encourage by resetting connections. No privilege or device node needed; requires an async-capable AEAD driver.

What to do

Boot a kernel carrying the linked stable commits, along with the rest of the tls async-decrypt series. Interim: disable async crypto offload for kTLS.

References