IB/rxe: Disable completion upcalls when a CQ is destroyed
This prevents the stack from accessing userspace objects while they are being torn down. One possible sequence of events: - Userspace program exits - ib_uverbs_cleanup_ucontext() runs, calling ib_destroy_qp(), ib_destroy_cq(), etc. and releasing/freeing the UCQ - The QP still has tasklets running, so it isn't destroyed yet - The CQ is referenced by the QP, so the CQ isn't destroyed yet - The UCQ is kfree()'d anyway - A send work request completes - rxe_send_complete() calls cq->ibcq.comp_handler() - ib_uverbs_comp_handler() runs and crashes; the event queue is checked for is_closed, but it has no way to check the ib_ucq_object before accessing it The reference counting on the CQ doesn't protect against this since the CQ hasn't been destroyed yet. There's no available interface to deregister the UCQ from the CQ, and it didn't appear that attempting to add reference counting to the UCQ was going to be a good way to go since this solution is much simpler. Fixes: 8700e3e7 ("Soft RoCE driver") Signed-off-by: Andrew Boyer <andrew.boyer@dell.com> Signed-off-by: Doug Ledford <dledford@redhat.com>
Showing
Please register or sign in to comment