diff --git a/drivers/scsi/dpt_i2o.c b/drivers/scsi/dpt_i2o.c
index b6af63ca980b4f1cb6be6acb2ca6762fe3f67548..7d1aac31ec8dcca36f70046966a9043f3d337f6e 100644
--- a/drivers/scsi/dpt_i2o.c
+++ b/drivers/scsi/dpt_i2o.c
@@ -1918,6 +1918,10 @@ static int adpt_i2o_passthru(adpt_hba* pHba, u32 __user *arg)
 		}
 		size = size>>16;
 		size *= 4;
+		if (size > MAX_MESSAGE_SIZE) {
+			rcode = EINVAL;
+			goto cleanup;
+		}
 		/* Copy in the user's I2O command */
 		if (copy_from_user (msg, user_msg, size)) {
 			rcode = -EFAULT;