From b1d41d678888fd1a51e4844ab583f7c47f9fb218 Mon Sep 17 00:00:00 2001
From: Austin Clements <amdragon@mit.edu>
Date: Wed, 1 Sep 2010 16:46:37 -0400
Subject: Remove the stack guard page.  Processes are now contiguous from 0 to
 proc->sz, which means our syscall argument validation is correct.  Add a
 pointer validation test and remove the stack test, which tested for the guard
 page.

---
 usertests.c | 60 +++++++++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 41 insertions(+), 19 deletions(-)

(limited to 'usertests.c')

diff --git a/usertests.c b/usertests.c
index 946565f..77495bf 100644
--- a/usertests.c
+++ b/usertests.c
@@ -3,6 +3,8 @@
 #include "user.h"
 #include "fs.h"
 #include "fcntl.h"
+#include "syscall.h"
+#include "traps.h"
 
 char buf[2048];
 char name[3];
@@ -1375,26 +1377,46 @@ sbrktest(void)
 }
 
 void
-stacktest(void)
+validateint(int *p)
 {
-  printf(stdout, "stack test\n");
-  char dummy = 1;
-  char *p = &dummy;
-  int ppid = getpid();
-  int pid = fork();
-  if(pid < 0){
-    printf(stdout, "fork failed\n");
-    exit();
-  }
-  if(pid == 0){
-    // should cause a trap:
-    p[-4096] = 'z';
-    kill(ppid);
-    printf(stdout, "stack test failed: page before stack was writeable\n");
-    exit();
+  int res;
+  asm("mov %%esp, %%ebx\n\t"
+      "mov %3, %%esp\n\t"
+      "int %2\n\t"
+      "mov %%ebx, %%esp" :
+      "=a" (res) :
+      "a" (SYS_sleep), "n" (T_SYSCALL), "c" (p) :
+      "ebx");
+}
+
+void
+validatetest(void)
+{
+  int hi = 1100*1024;
+
+  printf(stdout, "validate test\n");
+
+  uint p;
+  for (p = 0; p <= (uint)hi; p += 4096) {
+    int pid;
+    if ((pid = fork()) == 0) {
+      // try to crash the kernel by passing in a badly placed integer
+      validateint((int*)p);
+      exit();
+    }
+    sleep(0);
+    sleep(0);
+    kill(pid);
+    wait();
+
+    // try to crash the kernel by passing in a bad string pointer
+    if (link("nosuchfile", (char*)p) != -1) {
+      printf(stdout, "link should not succeed\n");
+      exit();
+    }
   }
-  wait();
-  printf(stdout, "stack test OK\n");
+
+  printf(stdout, "validate ok\n");
 }
 
 int
@@ -1408,8 +1430,8 @@ main(int argc, char *argv[])
   }
   close(open("usertests.ran", O_CREATE));
 
-  stacktest();
   sbrktest();
+  validatetest();
 
   opentest();
   writetest();
-- 
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