CVE-2025-40061

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

RDMA/rxe: Fix race in do_task() when draining

When do_task() exhausts its iteration budget (!ret), it sets the state to TASK_STATE_IDLE to reschedule, without a secondary check on the current task->state. This can overwrite the TASK_STATE_DRAINING state set by a concurrent call to rxe_cleanup_task() or rxe_disable_task().

While state changes are protected by a spinlock, both rxe_cleanup_task() and rxe_disable_task() release the lock while waiting for the task to finish draining in the while(!is_done(task)) loop. The race occurs if do_task() hits its iteration limit and acquires the lock in this window. The cleanup logic may then proceed while the task incorrectly reschedules itself, leading to a potential use-after-free.

This bug was introduced during the migration from tasklets to workqueues, where the special handling for the draining case was lost.

Fix this by restoring the original pre-migration behavior. If the state is TASK_STATE_DRAINING when iterations are exhausted, set cont to 1 to force a new loop iteration. This allows the task to finish its work, so that a subsequent iteration can reach the switch statement and correctly transition the state to TASK_STATE_DRAINED, stopping the task as intended.

Red Hat has evaluated this vulnerability as having a Moderate severity impact because exploitation requires local system privileges and winning a race condition during task cleanup in the Soft-RoCE driver. The affected rdma_rxe kernel module is not loaded by default in standard Red Hat Enterprise Linux installations and is only used when software RDMA over Ethernet is intentionally configured. Consequently, standard deployments that do not utilize Soft-RoCE are not exposed to this flaw, and the impact is primarily restricted to a local denial of service or potential memory corruption.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.