From: Parav Pandit <parav@xxxxxxxxxxxx>
Below cited commit missed to consider AF_IB and loopback code flow in
rdma_resolve_addr().
This leads to unbalanced cm_id refcount in cma_work_handler() which
puts the refcount which was not incremented in rdma_resolve_addr().
A call trace is observed with such code flow.
BUG: unable to handle kernel NULL pointer dereference at (null)
[<ffffffff96b67e16>] __mutex_lock_slowpath+0x166/0x1d0
[<ffffffff96b6715f>] mutex_lock+0x1f/0x2f
[<ffffffffc0beabb5>] cma_work_handler+0x25/0xa0
[<ffffffff964b9ebf>] process_one_work+0x17f/0x440
[<ffffffff964baf56>] worker_thread+0x126/0x3c0
Hence, hold the cm_id reference when scheduling resolve work item.
Fixes: 722c7b2bfead ("RDMA/{cma, core}: Avoid callback on rdma_addr_cancel()")
Signed-off-by: Parav Pandit <parav@xxxxxxxxxxxx>
Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxxxx>
---
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;
--
2.24.1
