Affected: Linux

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

RDMA/erdma: Fix CEQ tasklet use-after-free on removal

Each CEQ interrupt handler only schedules eqc->tasklet. The tasklet calls erdma_ceq_completion_handler(), which reads the DMA-coherent EQ ring through get_next_valid_eqe() and updates eq->dbrec through notify_eq().

erdma_ceqs_uninit() frees each CEQ IRQ and then destroys its EQ. free_irq() prevents another hard IRQ and waits for an in-flight handler, but it does not drain a tasklet that the handler already scheduled. The tasklet can therefore access eq->qbuf or eq->dbrec after erdma_eq_destroy() frees them.

Clearing ceq_cb->ready does not synchronize with a tasklet that already passed the check at the start of erdma_ceq_completion_handler().

Kill the tasklet after free_irq(), when no handler can schedule it again, and before erdma_ceq_uninit_one() releases the EQ buffers.