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Fix setxid race with thread creation

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This commit is contained in:
Ulrich Drepper 2010-03-05 11:23:28 -08:00
parent 01f1f5ee8b
commit 66f1b8eeb2
4 changed files with 39 additions and 8 deletions
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11
nptl/ChangeLog
View File

@ -1,3 +1,14 @@
2010-03-05 Andreas Schwab <schwab@redhat.com>
Ulrich Drepper <drepper@redhat.com>
* 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 <drepper@redhat.com>
* sysdeps/unix/sysv/linux/i386/i486/pthread_cond_timedwait.S:

13
nptl/allocatestack.c
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@ -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 <drepper@redhat.com>, 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;

9
nptl/pthread_create.c
View File

@ -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;

14
nptl/sysdeps/pthread/createthread.c
View File

@ -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 <drepper@redhat.com>, 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. */