TT#91151 add additional check for kernel module commands

Change-Id: I27f9ca4f03cd979ecbcf01e8fb1801a306f9d396

daemon/kernel.c

@@ -76,7 +76,8 @@ static int kernel_open_table(unsigned int id) {
 
 	ZERO(msg);
 	msg.cmd = REMG_NOOP;
-	msg.u.size = sizeof(msg);
+	msg.u.noop.size = sizeof(msg);
+	msg.u.noop.last_cmd = __REMG_LAST;
 	i = write(fd, &msg, sizeof(msg));
 	if (i <= 0)
 		goto fail;

kernel-module/xt_RTPENGINE.c

@@ -3293,8 +3293,10 @@ static inline ssize_t proc_control_read_write(struct file *file, char __user *ub
 
 	switch (msg->cmd) {
 		case REMG_NOOP:
-			if (msg->u.size != sizeof(*msg))
+			if (msg->u.noop.size != sizeof(*msg))
 				err = -EMSGSIZE;
+			if (msg->u.noop.last_cmd != __REMG_LAST)
+				err = -ERANGE;
 			break;
 
 		case REMG_ADD:

kernel-module/xt_RTPENGINE.h

@@ -146,9 +146,14 @@ struct rtpengine_stats_info {
 	struct rtpengine_ssrc_stats	ssrc_stats;	// output
 };
 
+struct rtpengine_noop_info {
+	size_t				size;
+	int				last_cmd;
+};
+
 struct rtpengine_message {
 	enum {
-		/* size: */
+		/* noop_info: */
 		REMG_NOOP = 1,
 
 		/* target_info: */
@@ -175,7 +180,7 @@ struct rtpengine_message {
 	}				cmd;
 
 	union {
-		size_t				size;
+		struct rtpengine_noop_info	noop;
 		struct rtpengine_target_info	target;
 		struct rtpengine_call_info	call;
 		struct rtpengine_stream_info	stream;