Revert "stack protector: use AT_RANDOM"

The AT_RANDOM changes broke setuid / setgid executables
such as "ping". When the linker executes a setuid program,
it cleans the environment, removing any invalid environment
entries, and adding "NULL"s to the end of the environment
array for each removed variable. Later on, we try to determine
the location of the aux environment variable, and get tripped
up by these extra NULLs.

Reverting this patch will get setuid executables working again,
but getauxval() is still broken for setuid programs because of
this bug.

This reverts commit e3a49a8661125f24aec8a1453e54b3b78005e21e.

Change-Id: I05c58a896b1fe32cfb5d95d43b096045cda0aa4a

1 files changed, 13 insertions, 3 deletions

diff --git a/tests/stack_protector_test.cpp b/tests/stack_protector_test.cpp
index ca90deac1..9cf3c38ab 100644
--- a/tests/stack_protector_test.cpp
+++ b/tests/stack_protector_test.cpp
@@ -56,7 +56,13 @@ struct stack_protector_checker {
 
     // Duplicate tid. gettid(2) bug? Seeing this would be very upsetting.
     ASSERT_TRUE(tids.find(tid) == tids.end());
-
+#ifdef __GLIBC__
+    // glibc uses the same guard for every thread. bionic uses a different guard for each one.
+#else
+    // Duplicate guard. Our bug. Note this is potentially flaky; we _could_ get the
+    // same guard for two threads, but it should be vanishingly unlikely.
+    ASSERT_TRUE(guards.find(guard) == guards.end());
+#endif
     // Uninitialized guard. Our bug. Note this is potentially flaky; we _could_ get
     // four random zero bytes, but it should be vanishingly unlikely.
     ASSERT_NE(guard, 0U);
@@ -72,7 +78,7 @@ static void* ThreadGuardHelper(void* arg) {
   return NULL;
 }
 
-TEST(stack_protector, same_guard_per_thread) {
+TEST(stack_protector, guard_per_thread) {
   stack_protector_checker checker;
   size_t thread_count = 10;
   for (size_t i = 0; i < thread_count; ++i) {
@@ -84,8 +90,12 @@ TEST(stack_protector, same_guard_per_thread) {
   }
   ASSERT_EQ(thread_count, checker.tids.size());
 
-  // bionic x86 and glibc uses the same guard for every thread.
+  // glibc uses the same guard for every thread. bionic uses a different guard for each one.
+#ifdef __BIONIC__
+  ASSERT_EQ(thread_count, checker.guards.size());
+#else
   ASSERT_EQ(1U, checker.guards.size());
+#endif
 }
 
 #endif