[PATCH] nvmet: always initialize cqe.result

[Daniel Wagner]

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@xxxxxxx>
---
Followup on the prevsious discussion on this topic[1]. I think we should add
this one to avoid transfering random stack values to the host when using RDMA.

[1] https://lore.kernel.org/linux-nvme/20240412061056.GA32319@xxxxxx/
---
 drivers/nvme/target/core.c             | 1 +
 drivers/nvme/target/fabrics-cmd-auth.c | 3 ---
 drivers/nvme/target/fabrics-cmd.c      | 6 ------
 3 files changed, 1 insertion(+), 9 deletions(-)

diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 06f0c587f343..4ff460ba2826 100644
--- a/drivers/nvme/target/core.c
+++ b/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;
diff --git a/drivers/nvme/target/fabrics-cmd-auth.c b/drivers/nvme/target/fabrics-cmd-auth.c
index d61b8c6ff3b2..cb34d644ed08 100644
--- a/drivers/nvme/target/fabrics-cmd-auth.c
+++ b/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) {
diff --git a/drivers/nvme/target/fabrics-cmd.c b/drivers/nvme/target/fabrics-cmd.c
index 042b379cbb36..69d77d34bec1 100644
--- a/drivers/nvme/target/fabrics-cmd.c
+++ b/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));

---
base-commit: 6bfd66808f973cf1bb234e54d0cd51a15bba2996
change-id: 20240612-nvmet-always-init-a794804edfed

Best regards,
-- 
Daniel Wagner <dwagner@xxxxxxx>