From 6e35aabee125999f4b3c01326f5339fa74a89259 Mon Sep 17 00:00:00 2001 From: Krishna Kumar Date: Fri, 29 Sep 2006 11:51:49 -0700 Subject: [PATCH] RDMA/cma: Fix device removal race The race is as follows: A process : cma_process_remove() calls cma_remove_id_dev(), which sets id state to CMA_DEVICE_REMOVAL and calls wait_event(dev_remove). B process : cma_req_handler() had incremented dev_remove, and calls cma_acquire_ib_dev() and on failure calls cma_release_remove(), which does a wake_up of cma_process_remove(). Then cma_req_handler() calls rdma_destroy_id(); A Process : cma_remove_id_dev() gets woken and checks the state of id, and since it is still (wrongly) CMA_DEVICE_REMOVAL, it calls notify_user(id) and if that fails, the caller - cma_process_remove() calls rdma_destroy_id(id). Two processes can call rdma_destroy_id(), resulting in one de-referencing kfreed id_priv. Fix is for process B to set CMA_DESTROYING in cma_req_handler() so that process A will return instead of doing a rdma_destroy_id(). Signed-off-by: Krishna Kumar Signed-off-by: Sean Hefty Signed-off-by: Roland Dreier --- drivers/infiniband/core/cma.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c index 69bb0892e88..f383a4f50ab 100644 --- a/drivers/infiniband/core/cma.c +++ b/drivers/infiniband/core/cma.c @@ -932,6 +932,7 @@ static int cma_req_handler(struct ib_cm_id *cm_id, struct ib_cm_event *ib_event) mutex_unlock(&lock); if (ret) { ret = -ENODEV; + cma_exch(conn_id, CMA_DESTROYING); cma_release_remove(conn_id); rdma_destroy_id(&conn_id->id); goto out; -- 2.20.1