commit 250667aaf69bcb701fea099caef6204ad84b1d32
author Josh Gao <jmgao@google.com> Fri Jun 24 13:04:09 2016 -0700
committer Josh Gao <jmgao@google.com> Tue Jun 28 15:52:59 2016 -0700
tree fe3891a4c1811da6e88975684704581cea05d2dc
parent 36ad0207d67ef395b003dbf75d2c0193d3b8e093

Take the arc4random lock before forking.

Bug: http://b/24675038
Test: stepped through a fork call in gdb
Change-Id: I09d20ff1d103d0c005f2a0cdd9b0a8710ab2392c

libc/bionic/libc_init_common.cpp

diff --git a/libc/bionic/libc_init_common.cpp b/libc/bionic/libc_init_common.cpp
index 0c9e87b..6f5b379 100644
--- a/libc/bionic/libc_init_common.cpp
+++ b/libc/bionic/libc_init_common.cpp
@@ -41,13 +41,14 @@
 #include <sys/time.h>
 #include <unistd.h>
 
+#include "private/KernelArgumentBlock.h"
+#include "private/WriteProtected.h"
 #include "private/bionic_auxv.h"
 #include "private/bionic_globals.h"
 #include "private/bionic_ssp.h"
 #include "private/bionic_tls.h"
-#include "private/KernelArgumentBlock.h"
 #include "private/libc_logging.h"
-#include "private/WriteProtected.h"
+#include "private/thread_private.h"
 #include "pthread_internal.h"
 
 extern "C" abort_msg_t** __abort_message_ptr;
@@ -123,6 +124,9 @@
   pthread_internal_t* main_thread = __get_thread();
   __pthread_internal_add(main_thread);
 
+  // Register atfork handlers to take and release the arc4random lock.
+  pthread_atfork(_thread_arc4_lock, _thread_arc4_unlock, _thread_arc4_unlock);
+
   __system_properties_init(); // Requires 'environ'.
 }