From: Parav Pandit parav@mellanox.com
[ 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@kernel.org Signed-off-by: Parav Pandit parav@mellanox.com Signed-off-by: Leon Romanovsky leonro@mellanox.com Reviewed-by: Jason Gunthorpe jgg@mellanox.com Signed-off-by: Jason Gunthorpe jgg@mellanox.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 43a6f07e0afe2..af1afc17b8bdf 100644 --- a/drivers/infiniband/core/cma.c +++ b/drivers/infiniband/core/cma.c @@ -3118,6 +3118,7 @@ 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; @@ -3144,6 +3145,7 @@ 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;