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From: Adhemerval Zanella <azanella@sourceware.org> To: glibc-cvs@sourceware.org Subject: [glibc/azanella/pthread-multiple-fixes] nptl: pthread_kill, pthread_cancel should fail after exit (bug 19193) Date: Fri, 20 Aug 2021 17:55:58 +0000 (GMT) [thread overview] Message-ID: <20210820175558.B137E38A8809@sourceware.org> (raw) https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=6ace783138d9d54bffdea8be3c0d06463bb976ea commit 6ace783138d9d54bffdea8be3c0d06463bb976ea Author: Florian Weimer <fweimer@redhat.com> Date: Fri Aug 20 13:31:21 2021 -0300 nptl: pthread_kill, pthread_cancel should fail after exit (bug 19193) This closes one remaining race condition related to bug 12889: if the thread already exited on the kernel side, returning ESRCH is not correct because that error is reserved for the thread IDs (pthread_t values) whose lifetime has ended. In case of a kernel-side exit and a valid thread ID, no signal needs to be sent and cancellation does not have an effect, so just return 0. sysdeps/pthread/tst-kill4.c triggers undefined behavior and is removed with this commit. Diff: --- nptl/pthread_cancel.c | 2 +- nptl/pthread_kill.c | 2 +- sysdeps/pthread/Makefile | 5 +++- sysdeps/pthread/tst-pthread_cancel-exited.c | 45 ++++++++++++++++++++++++++++ sysdeps/pthread/tst-pthread_kill-exited.c | 46 +++++++++++++++++++++++++++++ 5 files changed, 97 insertions(+), 3 deletions(-) diff --git a/nptl/pthread_cancel.c b/nptl/pthread_cancel.c index aed6c1ea47..ee65bf23ca 100644 --- a/nptl/pthread_cancel.c +++ b/nptl/pthread_cancel.c @@ -63,7 +63,7 @@ __pthread_cancel (pthread_t th) int state = atomic_load_acquire (&pd->joinstate); if (state == THREAD_STATE_EXITED || state == THREAD_STATE_EXITING) /* Not a valid thread handle. */ - return ESRCH; + return 0; static int init_sigcancel = 0; if (atomic_load_relaxed (&init_sigcancel) == 0) diff --git a/nptl/pthread_kill.c b/nptl/pthread_kill.c index f79a2b26fc..f935b1fb3e 100644 --- a/nptl/pthread_kill.c +++ b/nptl/pthread_kill.c @@ -46,7 +46,7 @@ __pthread_kill_internal (pthread_t threadid, int signo) ? INTERNAL_SYSCALL_ERRNO (val) : 0); } else - val = ESRCH; + val = 0; return val; } diff --git a/sysdeps/pthread/Makefile b/sysdeps/pthread/Makefile index 42f9fc5072..dedfa0d290 100644 --- a/sysdeps/pthread/Makefile +++ b/sysdeps/pthread/Makefile @@ -89,7 +89,7 @@ tests += tst-cnd-basic tst-mtx-trylock tst-cnd-broadcast \ tst-join8 tst-join9 tst-join10 tst-join11 tst-join12 tst-join13 \ tst-join14 tst-join15 \ tst-key1 tst-key2 tst-key3 tst-key4 \ - tst-kill1 tst-kill2 tst-kill3 tst-kill4 tst-kill5 tst-kill6 \ + tst-kill1 tst-kill2 tst-kill3 tst-kill5 tst-kill6 \ tst-locale1 tst-locale2 \ tst-memstream \ tst-mutex-errorcheck tst-mutex1 tst-mutex2 tst-mutex3 tst-mutex4 \ @@ -118,6 +118,9 @@ 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_cancel-exited \ + tst-pthread_kill-exited \ + # tests tests-time64 := \ tst-abstime-time64 \ diff --git a/sysdeps/pthread/tst-pthread_cancel-exited.c b/sysdeps/pthread/tst-pthread_cancel-exited.c new file mode 100644 index 0000000000..811c9bee07 --- /dev/null +++ b/sysdeps/pthread/tst-pthread_cancel-exited.c @@ -0,0 +1,45 @@ +/* Test that pthread_kill succeeds for an exited thread. + 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/>. */ + +/* This test verifies that pthread_kill returns 0 (and not ESRCH) for + a thread that has exited on the kernel side. */ + +#include <stddef.h> +#include <support/support.h> +#include <support/xthread.h> + +static void * +noop_thread (void *closure) +{ + return NULL; +} + +static int +do_test (void) +{ + pthread_t thr = xpthread_create (NULL, noop_thread, NULL); + + support_wait_for_thread_exit (); + + xpthread_cancel (thr); + xpthread_join (thr); + + return 0; +} + +#include <support/test-driver.c> diff --git a/sysdeps/pthread/tst-pthread_kill-exited.c b/sysdeps/pthread/tst-pthread_kill-exited.c new file mode 100644 index 0000000000..7575fb6d58 --- /dev/null +++ b/sysdeps/pthread/tst-pthread_kill-exited.c @@ -0,0 +1,46 @@ +/* Test that pthread_kill succeeds for an exited thread. + 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/>. */ + +/* This test verifies that pthread_kill returns 0 (and not ESRCH) for + a thread that has exited on the kernel side. */ + +#include <signal.h> +#include <stddef.h> +#include <support/support.h> +#include <support/xthread.h> + +static void * +noop_thread (void *closure) +{ + return NULL; +} + +static int +do_test (void) +{ + pthread_t thr = xpthread_create (NULL, noop_thread, NULL); + + support_wait_for_thread_exit (); + + xpthread_kill (thr, SIGUSR1); + xpthread_join (thr); + + return 0; +} + +#include <support/test-driver.c>
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