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nptl: Do not set signal mask on second setjmp return [BZ #28607] 

__libc_signal_restore_set was in the wrong place: It also ran
when setjmp returned the second time (after pthread_exit or
pthread_cancel).  This is observable with blocked pending
signals during thread exit.

Fixes commit b3cae39dcb
("nptl: Start new threads with all signals blocked [BZ #25098]").

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Florian Weimer 2021-11-24 08:59:54 +01:00
parent aac54dcd37
commit e186fc5a31
3 changed files with 48 additions and 2 deletions
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4
nptl/pthread_create.c
View File

@ -406,8 +406,6 @@ start_thread (void *arg)
unwind_buf.priv.data.prev = NULL;
unwind_buf.priv.data.cleanup = NULL;
__libc_signal_restore_set (&pd->sigmask);
/* Allow setxid from now onwards. */
if (__glibc_unlikely (atomic_exchange_acq (&pd->setxid_futex, 0) == -2))
futex_wake (&pd->setxid_futex, 1, FUTEX_PRIVATE);
@ -417,6 +415,8 @@ start_thread (void *arg)
/* Store the new cleanup handler info. */
THREAD_SETMEM (pd, cleanup_jmp_buf, &unwind_buf);
__libc_signal_restore_set (&pd->sigmask);
LIBC_PROBE (pthread_start, 3, (pthread_t) pd, pd->start_routine, pd->arg);
/* Run the code the user provided. */

1
sysdeps/pthread/Makefile
View File

@ -118,6 +118,7 @@ tests += tst-cnd-basic tst-mtx-trylock tst-cnd-broadcast \
tst-unload \
tst-unwind-thread \
tst-pt-vfork1 tst-pt-vfork2 tst-vfork1x tst-vfork2x \
tst-pthread-exit-signal \
tst-pthread-setuid-loop \
tst-pthread_cancel-exited \
tst-pthread_cancel-select-loop \

45
sysdeps/pthread/tst-pthread-exit-signal.c Normal file
View File

@ -0,0 +1,45 @@
/* Test that pending signals are not delivered on thread exit (bug 28607).
Copyright (C) 2021 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
/* Due to bug 28607, pthread_kill (or pthread_cancel) restored the
signal mask during during thread exit, triggering the delivery of a
blocked pending signal (SIGUSR1 in this test). */
#include <support/xthread.h>
#include <support/xsignal.h>
static void *
threadfunc (void *closure)
{
sigset_t sigmask;
sigfillset (&sigmask);
xpthread_sigmask (SIG_SETMASK, &sigmask, NULL);
xpthread_kill (pthread_self (), SIGUSR1);
pthread_exit (NULL);
return NULL;
}
static int
do_test (void)
{
pthread_t thr = xpthread_create (NULL, threadfunc, NULL);
xpthread_join (thr);
return 0;
}
#include <support/test-driver.c>