From a65ddfdc81f84240a930d2c3e1273c026bba62b3 Mon Sep 17 00:00:00 2001
From: Scott Haseley <shaseley@buffalo.edu>
Date: Sat, 18 Feb 2017 23:11:29 -0500
Subject: [PATCH] Beefed up consoletest for new ASST2.1. In its former
 incarnation, there is an easy hack to pass the test. This new version checks
 a little more of the write() spec and prevents the known exploitation.

---
 userland/testbin/consoletest/consoletest.c | 69 +++++++++++++++++++---
 1 file changed, 61 insertions(+), 8 deletions(-)

diff --git a/userland/testbin/consoletest/consoletest.c b/userland/testbin/consoletest/consoletest.c
index 6f91155..d3c6874 100644
--- a/userland/testbin/consoletest/consoletest.c
+++ b/userland/testbin/consoletest/consoletest.c
@@ -6,13 +6,13 @@
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
+ *	notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
+ *	notice, this list of conditions and the following disclaimer in the
+ *	documentation and/or other materials provided with the distribution.
  * 3. Neither the name of the University nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
+ *	may be used to endorse or promote products derived from this software
+ *	without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
@@ -32,27 +32,80 @@
  *
  * 	Tests whether console can be written to.
  *
- * This should run correctly when open and write syscalls are correctly implemented
+ *  This should run correctly when open and write syscalls are correctly
+ *  implemented.
  */
 
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
+#include <time.h>
 #include <unistd.h>
+#include <errno.h>
 #include <err.h>
 #include <test161/test161.h>
 
 // 23 Mar 2012 : GWA : BUFFER_COUNT must be even.
 
+#define STDOUT 1
+#define BUFFER_SIZE 1024
+
+#define NSEC_PER_MSEC 1000000ULL
+#define MSEC_PER_SEC 1000ULL
+
+static void *
+invalid_addr(int max) {
+	return (void *)((0x70000000) - (random() % max));
+}
+
+static void
+init_random() {
+	time_t sec;
+	unsigned long ns;
+	unsigned long long ms;
+
+	__time(&sec, &ns);
+	ms = (unsigned long long)sec * MSEC_PER_SEC;
+	ms += (ns / NSEC_PER_MSEC);
+	srandom((unsigned long)ms);
+}
+
 int
 main(int argc, char **argv)
 {
-
 	// 23 Mar 2012 : GWA : Assume argument passing is *not* supported.
 
 	(void) argc;
 	(void) argv;
 
-	secprintf(SECRET, "Able was i ere i saw elbA", "/testbin/consoletest");
+	int how_many, rv, i, len;
+	char buffer[BUFFER_SIZE];
+
+	init_random();
+
+	len = snsecprintf(BUFFER_SIZE, buffer, SECRET, "Able was i ere i saw elbA", "/testbin/consoletest");
+
+	how_many = (random() % 20) + 5;
+
+	for (i = 0; i < how_many; i++) {
+		rv = write(1, invalid_addr(0x1000000), len+1);
+		if (rv != -1) {
+			tprintf("Error: writing to invalid address!\n");
+		} else if (errno != EFAULT) {
+			tprintf("Error: Expected EFAULT, got %d\n", errno);
+		}
+	}
+
+	// Insert a '\0' somewhere in the secured string to thwart kprintf attack.
+	how_many = (random() % (len - 10)) + 5;
+	for (i = BUFFER_SIZE-1; i > how_many; i--) {
+		buffer[i] = buffer[i-1];
+	}
+	buffer[how_many] = '\0';
+	++len;
+
+	write(1, buffer, len);
+	write(1, "\n", 1);
+
 	return 0;
 }