From 66f1b8eeb20c49c8566abeeacf36540f258ad5f4 Mon Sep 17 00:00:00 2001 From: Ulrich Drepper Date: Fri, 5 Mar 2010 11:23:28 -0800 Subject: [PATCH] Fix setxid race with thread creation --- nptl/ChangeLog | 11 +++++++++++ nptl/allocatestack.c | 13 ++++++++++--- nptl/pthread_create.c | 9 ++++++++- nptl/sysdeps/pthread/createthread.c | 14 ++++++++++---- 4 files changed, 39 insertions(+), 8 deletions(-) diff --git a/nptl/ChangeLog b/nptl/ChangeLog index c81eb03b75..e0e1a5392f 100644 --- a/nptl/ChangeLog +++ b/nptl/ChangeLog @@ -1,3 +1,14 @@ +2010-03-05 Andreas Schwab + Ulrich Drepper + + * allocatestack.c (setxid_mark_thread): Delay handling of thread if + it is creating a thread or it is just being created. + * pthread_create.c (start_thread): Wake setxid thread if it is + waiting. + (__pthread_create_2_1): Initialize setxid_futex. + * sysdeps/pthread/createthread.c (do_clone): Wake setxid thread if it + is waiting. + 2010-01-15 Ulrich Drepper * sysdeps/unix/sysv/linux/i386/i486/pthread_cond_timedwait.S: diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c index 3c3585fe37..899c0e8eee 100644 --- a/nptl/allocatestack.c +++ b/nptl/allocatestack.c @@ -1,4 +1,4 @@ -/* Copyright (C) 2002-2007, 2009 Free Software Foundation, Inc. +/* Copyright (C) 2002-2007, 2009, 2010 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Ulrich Drepper , 2002. @@ -380,7 +380,7 @@ allocate_stack (const struct pthread_attr *attr, struct pthread **pdp, - TLS_TCB_SIZE - adj); #elif TLS_DTV_AT_TP pd = (struct pthread *) (((uintptr_t) attr->stackaddr - - __static_tls_size - adj) + - __static_tls_size - adj) - TLS_PRE_TCB_SIZE); #endif @@ -546,7 +546,7 @@ allocate_stack (const struct pthread_attr *attr, struct pthread **pdp, #ifndef __ASSUME_PRIVATE_FUTEX /* The thread must know when private futexes are supported. */ pd->header.private_futex = THREAD_GETMEM (THREAD_SELF, - header.private_futex); + header.private_futex); #endif #ifdef NEED_DL_SYSINFO @@ -969,6 +969,13 @@ setxid_mark_thread (struct xid_command *cmdp, struct pthread *t) { int ch; + /* Wait until this thread is cloned. */ + if (t->setxid_futex == -1 + && ! atomic_compare_and_exchange_bool_acq (&t->setxid_futex, -2, -1)) + do + lll_futex_wait (&t->setxid_futex, -2, LLL_PRIVATE); + while (t->setxid_futex == -2); + /* Don't let the thread exit before the setxid handler runs. */ t->setxid_futex = 0; 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 , 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; diff --git a/nptl/sysdeps/pthread/createthread.c b/nptl/sysdeps/pthread/createthread.c index 66fafe8050..3bb3915281 100644 --- a/nptl/sysdeps/pthread/createthread.c +++ b/nptl/sysdeps/pthread/createthread.c @@ -1,4 +1,4 @@ -/* Copyright (C) 2002-2007, 2008 Free Software Foundation, Inc. +/* Copyright (C) 2002-2007, 2008, 2010 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Ulrich Drepper , 2002. @@ -28,7 +28,7 @@ #include "kernel-features.h" -#define CLONE_SIGNAL (CLONE_SIGHAND | CLONE_THREAD) +#define CLONE_SIGNAL (CLONE_SIGHAND | CLONE_THREAD) /* Unless otherwise specified, the thread "register" is going to be initialized with a pointer to the TCB. */ @@ -72,8 +72,14 @@ do_clone (struct pthread *pd, const struct pthread_attr *attr, that cares whether the thread count is correct. */ atomic_increment (&__nptl_nthreads); - if (ARCH_CLONE (fct, STACK_VARIABLES_ARGS, clone_flags, - pd, &pd->tid, TLS_VALUE, &pd->tid) == -1) + int rc = ARCH_CLONE (fct, STACK_VARIABLES_ARGS, clone_flags, + pd, &pd->tid, TLS_VALUE, &pd->tid); + + /* 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); + + if (__builtin_expect (rc == -1, 0)) { atomic_decrement (&__nptl_nthreads); /* Oops, we lied for a second. */ -- 2.11.4.GIT