nvmet: always initialize cqe.result

The spec doesn't mandate that the first two double words (aka results)
for the command queue entry need to be set to 0 when they are not
used (not specified). Though, the target implemention returns 0 for TCP
and FC but not for RDMA.

Let's make RDMA behave the same and thus explicitly initializing the
result field. This prevents leaking any data from the stack.
Signed-off-by: Daniel Wagner <dwagner@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>

drivers/nvme/target/core.c

@@ -957,6 +957,7 @@ bool nvmet_req_init(struct nvmet_req *req, struct nvmet_cq *cq,
 	req->metadata_sg_cnt = 0;
 	req->transfer_len = 0;
 	req->metadata_len = 0;
+	req->cqe->result.u64 = 0;
 	req->cqe->status = 0;
 	req->cqe->sq_head = 0;
 	req->ns = NULL;

drivers/nvme/target/fabrics-cmd-auth.c

@@ -333,7 +333,6 @@ void nvmet_execute_auth_send(struct nvmet_req *req)
 		pr_debug("%s: ctrl %d qid %d nvme status %x error loc %d\n",
 			 __func__, ctrl->cntlid, req->sq->qid,
 			 status, req->error_loc);
-	req->cqe->result.u64 = 0;
 	if (req->sq->dhchap_step != NVME_AUTH_DHCHAP_MESSAGE_SUCCESS2 &&
 	    req->sq->dhchap_step != NVME_AUTH_DHCHAP_MESSAGE_FAILURE2) {
 		unsigned long auth_expire_secs = ctrl->kato ? ctrl->kato : 120;
@@ -516,8 +515,6 @@ void nvmet_execute_auth_receive(struct nvmet_req *req)
 	status = nvmet_copy_to_sgl(req, 0, d, al);
 	kfree(d);
 done:
-	req->cqe->result.u64 = 0;
-
 	if (req->sq->dhchap_step == NVME_AUTH_DHCHAP_MESSAGE_SUCCESS2)
 		nvmet_auth_sq_free(req->sq);
 	else if (req->sq->dhchap_step == NVME_AUTH_DHCHAP_MESSAGE_FAILURE1) {

drivers/nvme/target/fabrics-cmd.c

@@ -226,9 +226,6 @@ static void nvmet_execute_admin_connect(struct nvmet_req *req)
 	if (status)
 		goto out;
 
-	/* zero out initial completion result, assign values as needed */
-	req->cqe->result.u32 = 0;
-
 	if (c->recfmt != 0) {
 		pr_warn("invalid connect version (%d).\n",
 			le16_to_cpu(c->recfmt));
@@ -305,9 +302,6 @@ static void nvmet_execute_io_connect(struct nvmet_req *req)
 	if (status)
 		goto out;
 
-	/* zero out initial completion result, assign values as needed */
-	req->cqe->result.u32 = 0;
-
 	if (c->recfmt != 0) {
 		pr_warn("invalid connect version (%d).\n",
 			le16_to_cpu(c->recfmt));