[PATCH rdma-next v2] RDMA/irdma: Prevent rereg_mr for non-mem regions

[Jacob Moroni <jmoroni@google.com>]

When a QP/CQ/SRQ is created, a two step process is used
where the buffer is allocated in userspace and explicitly
registered with the normal reg_mr mechanism prior to creating
the actual QP/CQ/SRQ object.

These special registrations are indicated via an ABI field
so the driver knows that they do not have a valid mkey and
to skip the actual CQP command submission.

Since these are real MR objects from the core's perspective,
it is possible for a user application to invoke rereg_mr on them
and cause a real CQP op to be emitted with the zero-initialized
mkey value of 0.

Fix this by preventing rereg_mr on these special regions.

Fixes: 5ac388db27c4 ("RDMA/irdma: Add support to re-register a memory region")
Signed-off-by: Jacob Moroni <jmoroni@google.com>
---
V1->V2: Minor commit message fixes.

 drivers/infiniband/hw/irdma/verbs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/infiniband/hw/irdma/verbs.c b/drivers/infiniband/hw/irdma/verbs.c
index b79f5afe68..da8b4ae786 100644
--- a/drivers/infiniband/hw/irdma/verbs.c
+++ b/drivers/infiniband/hw/irdma/verbs.c
@@ -3791,6 +3791,9 @@ static struct ib_mr *irdma_rereg_user_mr(struct ib_mr *ib_mr, int flags,
 	if (flags & ~(IB_MR_REREG_TRANS | IB_MR_REREG_PD | IB_MR_REREG_ACCESS))
 		return ERR_PTR(-EOPNOTSUPP);
 
+	if (iwmr->type != IRDMA_MEMREG_TYPE_MEM)
+		return ERR_PTR(-EINVAL);
+
 	if (dmabuf_revocable) {
 		umem_dmabuf = to_ib_umem_dmabuf(iwmr->region);
 
-- 
2.54.0.1189.g8c84645362-goog