Fix setxid race with thread creation

1 files changed, 8 insertions, 1 deletions

diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
index 89938b3fb8..194a8ba0ab 100644
--- a/nptl/pthread_create.c
+++ b/nptl/pthread_create.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 2002-2007,2008,2009 Free Software Foundation, Inc.
+/* Copyright (C) 2002-2007,2008,2009,2010 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
 
@@ -239,6 +239,10 @@ start_thread (void *arg)
   /* Initialize resolver state pointer.  */
   __resp = &pd->res;
 
+  /* Allow setxid from now onwards.  */
+  if (__builtin_expect (atomic_exchange_acq (&pd->setxid_futex, 0) == -2, 0))
+    lll_futex_wake (&pd->setxid_futex, 1, LLL_PRIVATE);
+
 #ifdef __NR_set_robust_list
 # ifndef __ASSUME_SET_ROBUST_LIST
   if (__set_robust_list_avail >= 0)
@@ -538,6 +542,9 @@ __pthread_create_2_1 (newthread, attr, start_routine, arg)
 	}
     }
 
+  /* Don't allow setxid until cloned. */
+  pd->setxid_futex = -1;
+
   /* Pass the descriptor to the caller.  */
   *newthread = (pthread_t) pd;