ksmbd: fix outstanding credits related bugs

commit 376b913382 upstream.

outstanding credits must be initialized to 0,
because it means the sum of credits consumed by
in-flight requests.
And outstanding credits must be compared with
total credits in smb2_validate_credit_charge(),
because total credits are the sum of credits
granted by ksmbd.

This patch fix the following error,
while frametest with Windows clients:

Limits exceeding the maximum allowable outstanding requests,
given : 128, pending : 8065

Fixes: b589f5db6d ("ksmbd: limits exceeding the maximum allowable outstanding requests")
Cc: stable@vger.kernel.org
Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com>
Reported-by: Yufan Chen <wiz.chen@gmail.com>
Tested-by: Yufan Chen <wiz.chen@gmail.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/ksmbd/connection.c

@@ -62,7 +62,7 @@ struct ksmbd_conn *ksmbd_conn_alloc(void)
 	atomic_set(&conn->req_running, 0);
 	atomic_set(&conn->r_count, 0);
 	conn->total_credits = 1;
-	conn->outstanding_credits = 1;
+	conn->outstanding_credits = 0;
 
 	init_waitqueue_head(&conn->req_running_q);
 	INIT_LIST_HEAD(&conn->conns_list);

fs/ksmbd/smb2misc.c

@@ -339,7 +339,7 @@ static int smb2_validate_credit_charge(struct ksmbd_conn *conn,
 		ret = 1;
 	}
 
-	if ((u64)conn->outstanding_credits + credit_charge > conn->vals->max_credits) {
+	if ((u64)conn->outstanding_credits + credit_charge > conn->total_credits) {
 		ksmbd_debug(SMB, "Limits exceeding the maximum allowable outstanding requests, given : %u, pending : %u\n",
 			    credit_charge, conn->outstanding_credits);
 		ret = 1;

fs/ksmbd/smb_common.c

@@ -140,8 +140,10 @@ int ksmbd_verify_smb_message(struct ksmbd_work *work)
 
 	hdr = work->request_buf;
 	if (*(__le32 *)hdr->Protocol == SMB1_PROTO_NUMBER &&
-	    hdr->Command == SMB_COM_NEGOTIATE)
+	    hdr->Command == SMB_COM_NEGOTIATE) {
+		work->conn->outstanding_credits++;
 		return 0;
+	}
 
 	return -EINVAL;
 }