[PATCH rdma-next] RDMA/irdma: Prevent user-triggered null deref on QP create

[Jacob Moroni <jmoroni@google.com>]

Previously, the user QP creation path would only attempt to
populate iwqp->iwpbl if the user-provided req.user_wqe_bufs
field was non-zero. The problem is that iwqp->iwpbl is
unconditionally dereferenced later on in irdma_setup_virt_qp.

While there was a check for iwqp->iwpbl != NULL, this check
would only occur if req.user_wqe_bufs was non-zero. The end
result is that a user could send a zero user_wqe_bufs value
and trigger a null ptr deref.

Fix this by unconditionally calling irdma_get_pbl and bailing
if it fails, similar to the CQ and SRQ paths.

Fixes: b48c24c2d710 ("RDMA/irdma: Implement device supported verb APIs")
Signed-off-by: Jacob Moroni <jmoroni@google.com>
---
 drivers/infiniband/hw/irdma/verbs.c | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/drivers/infiniband/hw/irdma/verbs.c b/drivers/infiniband/hw/irdma/verbs.c
index 4c0ea7c9b9..4124e4d732 100644
--- a/drivers/infiniband/hw/irdma/verbs.c
+++ b/drivers/infiniband/hw/irdma/verbs.c
@@ -638,17 +638,16 @@ static int irdma_setup_umode_qp(struct ib_udata *udata,
 
 	iwqp->ctx_info.qp_compl_ctx = req.user_compl_ctx;
 	iwqp->user_mode = 1;
-	if (req.user_wqe_bufs) {
-		spin_lock_irqsave(&ucontext->qp_reg_mem_list_lock, flags);
-		iwqp->iwpbl = irdma_get_pbl((unsigned long)req.user_wqe_bufs,
-					    &ucontext->qp_reg_mem_list);
-		spin_unlock_irqrestore(&ucontext->qp_reg_mem_list_lock, flags);
-
-		if (!iwqp->iwpbl) {
-			ret = -ENODATA;
-			ibdev_dbg(&iwdev->ibdev, "VERBS: no pbl info\n");
-			return ret;
-		}
+
+	spin_lock_irqsave(&ucontext->qp_reg_mem_list_lock, flags);
+	iwqp->iwpbl = irdma_get_pbl((unsigned long)req.user_wqe_bufs,
+				    &ucontext->qp_reg_mem_list);
+	spin_unlock_irqrestore(&ucontext->qp_reg_mem_list_lock, flags);
+
+	if (!iwqp->iwpbl) {
+		ret = -ENODATA;
+		ibdev_dbg(&iwdev->ibdev, "VERBS: no pbl info\n");
+		return ret;
 	}
 
 	if (!ucontext->use_raw_attrs) {
-- 
2.54.0.1189.g8c84645362-goog