From: Parav Pandit <parav@xxxxxxxxxxxx>
[ Upstream commit b4fb4cc5ba83b20dae13cef116c33648e81d2f44 ]
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)
[<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 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@xxxxxxxxxx
Signed-off-by: Parav Pandit <parav@xxxxxxxxxxxx>
Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxxxx>
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 50052e9a17318..9008937f8ed86 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -3091,6 +3091,7 @@ 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;
@@ -3117,6 +3118,7 @@ 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;
--
2.20.1
