ksmbd: smbdirect: verify remaining_data_length respects max_fragmented_recv_size

This is inspired by the check for data_offset + data_length.

Cc: Steve French <[email protected]>
Cc: Tom Talpey <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Fixes: 2ea086e ("ksmbd: add buffer validation for smb direct")
Acked-by: Namjae Jeon <[email protected]>
Signed-off-by: Stefan Metzmacher <[email protected]>
Signed-off-by: Steve French <[email protected]>

Author: metze-samba

fs/smb/server/transport_rdma.c

@@ -554,7 +554,7 @@ static void recv_done(struct ib_cq *cq, struct ib_wc *wc)
 	case SMB_DIRECT_MSG_DATA_TRANSFER: {
 		struct smb_direct_data_transfer *data_transfer =
 			(struct smb_direct_data_transfer *)recvmsg->packet;
-		unsigned int data_offset, data_length;
+		u32 remaining_data_length, data_offset, data_length;
 		int avail_recvmsg_count, receive_credits;
 
 		if (wc->byte_len <
@@ -564,6 +564,7 @@ static void recv_done(struct ib_cq *cq, struct ib_wc *wc)
 			return;
 		}
 
+		remaining_data_length = le32_to_cpu(data_transfer->remaining_data_length);
 		data_length = le32_to_cpu(data_transfer->data_length);
 		data_offset = le32_to_cpu(data_transfer->data_offset);
 		if (wc->byte_len < data_offset ||
@@ -572,6 +573,14 @@ static void recv_done(struct ib_cq *cq, struct ib_wc *wc)
 			smb_direct_disconnect_rdma_connection(t);
 			return;
 		}
+		if (remaining_data_length > t->max_fragmented_recv_size ||
+		    data_length > t->max_fragmented_recv_size ||
+		    (u64)remaining_data_length + (u64)data_length >
+		    (u64)t->max_fragmented_recv_size) {
+			put_recvmsg(t, recvmsg);
+			smb_direct_disconnect_rdma_connection(t);
+			return;
+		}
 
 		if (data_length) {
 			if (t->full_packet_received)