Re: [PATCH rdma-next 2/3] RDMA/core: Fix check of device in rdma_listen()

[Jason Gunthorpe <jgg@nvidia.com>]

On Sun, Apr 18, 2021 at 04:55:53PM +0300, Leon Romanovsky wrote:
> From: Shay Drory <shayd@nvidia.com>
> 
> rdma_listen() checks if device already attached to rdma_id_priv,
> based on the response the its decide to what to listen, however
> this is different when the listeners are canceled.
> 
> This leads to a mismatch between rdma_listen() and cma_cancel_operation(),
> and causes to bellow wild-memory-access. Fix it by aligning rdma_listen()
> according to the cma_cancel_operation().

So this is happening because the error unwind in rdma_bind_addr() is
taking the exit path and calling cma_release_dev()?

This allows rdma_listen() to be called with a bogus device pointer
which precipitates this UAF during destroy.

However, I think rdma_bind_addr() should not allow the bogus device
pointer to leak out at all, since the ULP could see it. It really is
invalid to have it present no matter what.

This would make cma_release_dev() and _cma_attach_to_dev()
symmetrical - what do you think?

diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 2dc302a83014ae..91f6d968b46f65 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -474,6 +474,7 @@ static void cma_release_dev(struct rdma_id_private *id_priv)
 	list_del(&id_priv->list);
 	cma_dev_put(id_priv->cma_dev);
 	id_priv->cma_dev = NULL;
+	id_priv->id.device = NULL;
 	if (id_priv->id.route.addr.dev_addr.sgid_attr) {
 		rdma_put_gid_attr(id_priv->id.route.addr.dev_addr.sgid_attr);
 		id_priv->id.route.addr.dev_addr.sgid_attr = NULL;