commit bfe68fe3c475fe34bed4e017d6e63196c305c934

Author: Florian Weimer <fweimer@redhat.com>

Date:   Wed Nov 24 08:59:54 2021 +0100

    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 b3cae39dcbfa2432b3f3aa28854d8ac57f0de1b8

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

    Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

    (cherry picked from commit e186fc5a31e46f2cbf5ea1a75223b4412907f3d8)

diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c

index bc213f0bc4e948bd..3db0c9fdf40ae2bf 100644

--- a/nptl/pthread_create.c

+++ b/nptl/pthread_create.c

@@ -407,8 +407,6 @@ 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);

@@ -418,6 +416,8 @@ 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.  */

diff --git a/sysdeps/pthread/Makefile b/sysdeps/pthread/Makefile

index df8943f4860a39d8..c65710169697ad95 100644

--- a/sysdeps/pthread/Makefile

+++ b/sysdeps/pthread/Makefile

@@ -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 \

diff --git a/sysdeps/pthread/tst-pthread-exit-signal.c b/sysdeps/pthread/tst-pthread-exit-signal.c

new file mode 100644

index 0000000000000000..b4526fe663671068

--- /dev/null

+++ b/sysdeps/pthread/tst-pthread-exit-signal.c

@@ -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>