CVE-2026-72115

Summary

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

can: bcm: track a single source interface for ANYDEV timeout/throttle ops

An ANYDEV rx op (ifindex == 0) with an active RX timeout and/or throttle timer has no defined semantics when matching frames arrive from several interfaces: bcm_rx_handler() can run concurrently for the same op on different CPUs, racing hrtimer_cancel()/ bcm_rx_starttimer() against bcm_rx_timeout_handler() and causing spurious RX_TIMEOUT notifications and last_frames corruption. The same concurrency lets throttled multiplex frames from different interfaces clobber the single rx_ifindex/rx_stamp fields shared by the op.

Add op->if_detected to track the first interface that delivers a matching frame while a timeout/throttle timer is configured, and reject frames from any other interface for that op. The claim is decided in bcm_rx_handler() before hrtimer_cancel() touches op->timer, so a rejected frame can never disturb the claimed interface's watchdog. RTR-mode ops are excluded via RX_RTR_FRAME, independent of kt_ival1/kt_ival2, since those may briefly hold a stale value from an earlier non-RTR configuration.

The claim is released in bcm_notify() on NETDEV_UNREGISTER and in bcm_rx_setup() when SETTIMER reconfigures the timer values.

A (re-)claim is only possible on CAN devices in NETREG_REGISTERED dev->reg_state to cover the release in bcm_notify() where reg_state becomes NETREG_UNREGISTERING until synchronize_net().

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/18b45251e74e35668f0dd0c470549384ae191ecf
• https://git.kernel.org/stable/c/3ff8c24b421070a2db99a5cdb86edc9ff339418e
• https://git.kernel.org/stable/c/eca8b44d51fc6ab61022258ec968e55e3073b79e
• https://git.kernel.org/stable/c/b6317022b685a430a3ae420456716e3c0c02ef4b
• https://git.kernel.org/stable/c/2f5976f54a04e9f18b25283036ac3136be453b17

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