From b4fb4cc5ba83b20dae13cef116c33648e81d2f44 Mon Sep 17 00:00:00 2001 From: Parav Pandit Date: Sun, 26 Jan 2020 16:26:46 +0200 Subject: [PATCH] RDMA/cma: Fix unbalanced cm_id reference count during address resolve Below commit missed the AF_IB and loopback code flow in rdma_resolve_addr(). This leads to an unbalanced cm_id refcount in cma_work_handler() which puts the refcount which was not incremented prior to queuing the work. A call trace is observed with such code flow: BUG: unable to handle kernel NULL pointer dereference at (null) [] __mutex_lock_slowpath+0x166/0x1d0 [] mutex_lock+0x1f/0x2f [] cma_work_handler+0x25/0xa0 [] process_one_work+0x17f/0x440 [] worker_thread+0x126/0x3c0 Hence, hold the cm_id reference when scheduling the resolve work item. Fixes: 722c7b2bfead ("RDMA/{cma, core}: Avoid callback on rdma_addr_cancel()") Link: https://lore.kernel.org/r/20200126142652.104803-2-leon@kernel.org Signed-off-by: Parav Pandit Signed-off-by: Leon Romanovsky Reviewed-by: Jason Gunthorpe Signed-off-by: Jason Gunthorpe --- drivers/infiniband/core/cma.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c index 55a9afacfedd..72f032160c4b 100644 --- a/drivers/infiniband/core/cma.c +++ b/drivers/infiniband/core/cma.c @@ -3148,6 +3148,7 @@ static int cma_resolve_loopback(struct rdma_id_private *id_priv) rdma_addr_get_sgid(&id_priv->id.route.addr.dev_addr, &gid); rdma_addr_set_dgid(&id_priv->id.route.addr.dev_addr, &gid); + atomic_inc(&id_priv->refcount); cma_init_resolve_addr_work(work, id_priv); queue_work(cma_wq, &work->work); return 0; @@ -3174,6 +3175,7 @@ static int cma_resolve_ib_addr(struct rdma_id_private *id_priv) rdma_addr_set_dgid(&id_priv->id.route.addr.dev_addr, (union ib_gid *) &(((struct sockaddr_ib *) &id_priv->id.route.addr.dst_addr)->sib_addr)); + atomic_inc(&id_priv->refcount); cma_init_resolve_addr_work(work, id_priv); queue_work(cma_wq, &work->work); return 0; -- 2.39.5