CyberRota Analysis
AI-GeneratedThe vulnerability affects the Linux kernel's CAN (Controller Area Network) subsystem, specifically in the bcm.c code, where a missing device reference count during filter removal can lead to a stale CAN filter pointing to a soon-to-be-freed memory location. This flaw could result in potential memory corruption or crashes if a device is unregistered concurrently, impacting system stability and reliability. Organizations utilizing Linux systems that implement CAN functionality should prioritize addressing this issue to mitigate risks associated with concurrent device management.
Original NVD Description
In the Linux kernel, the following vulnerability has been resolved: can: bcm: add missing device refcount for CAN filter removal sashiko-bot remarked a problem with a concurrent device unregistration in isotp.c which also is present in the bcm.c code. A former fix for raw.c commit c275a176e4b6 ("can: raw: add missing refcount for memory leak fix") introduced a netdevice_tracker which solves the issue for bcm.c too. bcm_release(), bcm_delete_rx_op() and bcm_notifier() relied on dev_get_by_index(ifindex) to re-find the device for an rx_op before unregistering its filter. If a concurrent NETDEV_UNREGISTER has already unlisted the device from the ifindex table, that lookup fails and can_rx_unregister() is silently skipped, leaving a stale CAN filter pointing at the soon-to-be-freed bcm_op/socket. Hold a netdev_hold()/netdev_put() tracked reference on op->rx_reg_dev from the moment the rx filter is registered in bcm_rx_setup() until it is unregistered in bcm_rx_unreg(), and use that reference directly in bcm_release() and bcm_delete_rx_op() instead of re-looking the device up by ifindex.