[PATCH] nvmet: Free the old negotiation state when restarting authentication

[Guixin Liu <kanie@linux.alibaba.com>]

Restarting a DH-HMAC-CHAP negotiation with SEND(NEGOTIATE) resets
sq->dhchap_step but does not release the previous c1/c2/skey, which
are only freed in nvmet_auth_sq_free() at teardown.  The next
CHALLENGE/REPLY exchange then overwrites those pointers with fresh
allocations.

An unauthenticated host can repeat the negotiate message endlessly,
leaking a few dozen bytes per round and slowly exhausting target
memory.

Clear the old negotiation state with nvmet_auth_sq_free() before
setting up the new one.

Fixes: db1312dd95488 ("nvmet: implement basic In-Band Authentication")
Cc: stable@vger.kernel.org
Signed-off-by: Guixin Liu <kanie@linux.alibaba.com>
---
 drivers/nvme/target/fabrics-cmd-auth.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/nvme/target/fabrics-cmd-auth.c b/drivers/nvme/target/fabrics-cmd-auth.c
index bc49b48cdd63..3d9840d37a8b 100644
--- a/drivers/nvme/target/fabrics-cmd-auth.c
+++ b/drivers/nvme/target/fabrics-cmd-auth.c
@@ -330,6 +330,7 @@ void nvmet_execute_auth_send(struct nvmet_req *req)
 			/* Restart negotiation */
 			pr_debug("%s: ctrl %d qid %d reset negotiation\n",
 				 __func__, ctrl->cntlid, req->sq->qid);
+			nvmet_auth_sq_free(req->sq);
 			if (!req->sq->qid) {
 				dhchap_status = nvmet_setup_auth(ctrl, req->sq,
 								 true);
-- 
2.43.7