CVE-2026-63874net: mctp: usb: fix race between urb completion and rx_retry cancellation

Official description

In the Linux kernel, the following vulnerability has been resolved: net: mctp: usb: fix race between urb completion and rx_retry cancellation It's possible that sequencing between setting ->stopped and cancelling the rx_retry work (in ndo_stop) could leave us with an urb queued: T1: ndo_stop T2: rx_retry_work ------------ ---------------- LD: ->stopped => false ST: ->stopped <= true usb_kill_urb() mctp_usb_rx_queue() usb_submit_urb() cancel_delayed_work_sync() That urb completion can then re-schedule rx_retry_work. Strenghen the sequencing between the stop (preventing another requeue) and the cancel by updating both atomically under a new rx lock. After setting ->rx_stopped, and cancelling pending work, we know that the requeue cannot occur, so all that's left is killing any pending urb.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/9c46f3ee1837f6881cb99a52ffecb2760f11dc73
• https://git.kernel.org/stable/c/d90feaa3f74bea8dafb6494631a194c70e547d94
• https://git.kernel.org/stable/c/54665dce982689e2fd99b32e9a0dcc204fda8a51