thunderbolt: Don't access a DP tunnel after its DPRX read was canceled

Overview

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

thunderbolt: Don't access a DP tunnel after its DPRX read was canceled

tb_dp_dprx_work() checks ->dprx_canceled before it takes tb->lock so it misses a tb_dp_dprx_stop() that could not cancel the already running work. It then polls the DPRX capabilities and runs the callback for a tunnel that has already been torn down while the domain is suspending or going away.

This can be hit by cancelling the DPRX read from outside the ordered tb->wq: During suspend tb_disconnect_and_release_dp() does just this and with a later patch tb_stop() will do it as well. The latter in combination with the Apple NHI where the DPRX read never completed is how I hit this.

Check the flag with tb->lock held instead and check it again in tb_dp_tunnel_active() because the callback runs after the lock has been dropped again.

Also clear the flag in tb_dp_dprx_start() so that it only ever describes the work that is currently in flight.

Affected

• Linux >= d6d458d42e1e1544a18f37f1d5c840e00d5261b9 < 405a969c0b3356639116db89ab367be1d64b77c0
• Linux >= d6d458d42e1e1544a18f37f1d5c840e00d5261b9 < 2c2fd6a7fd5e1218db7e17336fc1a0393b6949e6
• Linux >= d6d458d42e1e1544a18f37f1d5c840e00d5261b9 < 419fa32fa5bc2d7fb9d0d15d5630b1c1090808b3
• Linux 6.14

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.