staging: lustre: integer overflow in obd_ioctl_is_invalid()

The obd_ioctl_getdata() function caps "data->ioc_len" at
OBD_MAX_IOCTL_BUFFER and then calls this obd_ioctl_is_invalid() to check
that the other values inside data are valid.

There are several lengths inside data but when they are added together
they must not be larger than "data->ioc_len".  The checks against
"(data->ioc_inllen1 > (1<<30))" are supposed to ensure that the addition
does not have an integer overflow.  But "(1<<30) * 4" actually can
overflow 32 bits, so the checks are insufficient.

I have changed it to "> OBD_MAX_IOCTL_BUFFER" instead.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/include/lustre_lib.h

@@ -179,24 +179,25 @@ static inline int obd_ioctl_packlen(struct obd_ioctl_data *data)
 
 static inline int obd_ioctl_is_invalid(struct obd_ioctl_data *data)
 {
-	if (data->ioc_len > (1<<30)) {
-		CERROR("OBD ioctl: ioc_len larger than 1<<30\n");
+	if (data->ioc_len > OBD_MAX_IOCTL_BUFFER) {
+		CERROR("OBD ioctl: ioc_len larger than %d\n",
+		       OBD_MAX_IOCTL_BUFFER);
 		return 1;
 	}
-	if (data->ioc_inllen1 > (1<<30)) {
-		CERROR("OBD ioctl: ioc_inllen1 larger than 1<<30\n");
+	if (data->ioc_inllen1 > OBD_MAX_IOCTL_BUFFER) {
+		CERROR("OBD ioctl: ioc_inllen1 larger than ioc_len\n");
 		return 1;
 	}
-	if (data->ioc_inllen2 > (1<<30)) {
-		CERROR("OBD ioctl: ioc_inllen2 larger than 1<<30\n");
+	if (data->ioc_inllen2 > OBD_MAX_IOCTL_BUFFER) {
+		CERROR("OBD ioctl: ioc_inllen2 larger than ioc_len\n");
 		return 1;
 	}
-	if (data->ioc_inllen3 > (1<<30)) {
-		CERROR("OBD ioctl: ioc_inllen3 larger than 1<<30\n");
+	if (data->ioc_inllen3 > OBD_MAX_IOCTL_BUFFER) {
+		CERROR("OBD ioctl: ioc_inllen3 larger than ioc_len\n");
 		return 1;
 	}
-	if (data->ioc_inllen4 > (1<<30)) {
-		CERROR("OBD ioctl: ioc_inllen4 larger than 1<<30\n");
+	if (data->ioc_inllen4 > OBD_MAX_IOCTL_BUFFER) {
+		CERROR("OBD ioctl: ioc_inllen4 larger than ioc_len\n");
 		return 1;
 	}
 	if (data->ioc_inlbuf1 && !data->ioc_inllen1) {