From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2154) id 8FE2A385C40F; Thu, 15 Jul 2021 21:40:22 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 8FE2A385C40F Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Stan Shebs To: glibc-cvs@sourceware.org Subject: [glibc/google/grte/v5-2.27/master] Read f->func.cxa under the lock. X-Act-Checkin: glibc X-Git-Author: Vitaly Buka X-Git-Refname: refs/heads/google/grte/v5-2.27/master X-Git-Oldrev: 0ad524ba97cc582049e92ea22550169e161e307a X-Git-Newrev: e4187ca242dabf1b7aa7f400fb22911766771a50 Message-Id: <20210715214022.8FE2A385C40F@sourceware.org> Date: Thu, 15 Jul 2021 21:40:22 +0000 (GMT) X-BeenThere: glibc-cvs@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Glibc-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 15 Jul 2021 21:40:22 -0000 https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=e4187ca242dabf1b7aa7f400fb22911766771a50 commit e4187ca242dabf1b7aa7f400fb22911766771a50 Author: Vitaly Buka Date: Thu Jul 15 14:39:33 2021 -0700 Read f->func.cxa under the lock. Diff: --- stdlib/Makefile | 4 +- stdlib/exit.c | 28 ++++++---- stdlib/test-cxa_atexit-race2.c | 114 +++++++++++++++++++++++++++++++++++++++++ 3 files changed, 135 insertions(+), 11 deletions(-) diff --git a/stdlib/Makefile b/stdlib/Makefile index a9ad849531..c11a794d2a 100644 --- a/stdlib/Makefile +++ b/stdlib/Makefile @@ -82,7 +82,8 @@ tests := tst-strtol tst-strtod testmb testrand testsort testdiv \ tst-width-stdint tst-strfrom tst-strfrom-locale \ tst-getrandom tst-atexit tst-at_quick_exit \ tst-cxa_atexit tst-on_exit test-atexit-race \ - test-at_quick_exit-race test-cxa_atexit-race \ + test-at_quick_exit-race test-cxa_atexit-race \ + test-cxa_atexit-race2 \ test-on_exit-race test-dlclose-exit-race \ tst-makecontext-align test-bz22786 @@ -97,6 +98,7 @@ endif LDLIBS-test-atexit-race = $(shared-thread-library) LDLIBS-test-at_quick_exit-race = $(shared-thread-library) LDLIBS-test-cxa_atexit-race = $(shared-thread-library) +LDLIBS-test-cxa_atexit-race2 = $(shared-thread-library) LDLIBS-test-on_exit-race = $(shared-thread-library) LDLIBS-test-dlclose-exit-race = $(shared-thread-library) $(libdl) diff --git a/stdlib/exit.c b/stdlib/exit.c index 0a4944fa05..9c669fd1a8 100644 --- a/stdlib/exit.c +++ b/stdlib/exit.c @@ -45,6 +45,8 @@ __run_exit_handlers (int status, struct exit_function_list **listp, if (run_dtors) __call_tls_dtors (); + __libc_lock_lock (__exit_funcs_lock); + /* We do it this way to handle recursive calls to exit () made by the functions registered with `atexit' and `on_exit'. We call everyone on the list and use the status value in the last @@ -53,8 +55,6 @@ __run_exit_handlers (int status, struct exit_function_list **listp, { struct exit_function_list *cur; - __libc_lock_lock (__exit_funcs_lock); - restart: cur = *listp; @@ -63,7 +63,6 @@ __run_exit_handlers (int status, struct exit_function_list **listp, /* Exit processing complete. We will not allow any more atexit/on_exit registrations. */ __exit_funcs_done = true; - __libc_lock_unlock (__exit_funcs_lock); break; } @@ -72,44 +71,52 @@ __run_exit_handlers (int status, struct exit_function_list **listp, struct exit_function *const f = &cur->fns[--cur->idx]; const uint64_t new_exitfn_called = __new_exitfn_called; - /* Unlock the list while we call a foreign function. */ - __libc_lock_unlock (__exit_funcs_lock); switch (f->flavor) { void (*atfct) (void); void (*onfct) (int status, void *arg); void (*cxafct) (void *arg, int status); + void *arg; case ef_free: case ef_us: break; case ef_on: onfct = f->func.on.fn; + arg = f->func.on.arg; #ifdef PTR_DEMANGLE PTR_DEMANGLE (onfct); #endif - onfct (status, f->func.on.arg); + /* Unlock the list while we call a foreign function. */ + __libc_lock_unlock (__exit_funcs_lock); + onfct (status, arg); + __libc_lock_lock (__exit_funcs_lock); break; case ef_at: atfct = f->func.at; #ifdef PTR_DEMANGLE PTR_DEMANGLE (atfct); #endif + /* Unlock the list while we call a foreign function. */ + __libc_lock_unlock (__exit_funcs_lock); atfct (); + __libc_lock_lock (__exit_funcs_lock); break; case ef_cxa: /* To avoid dlclose/exit race calling cxafct twice (BZ 22180), we must mark this function as ef_free. */ f->flavor = ef_free; cxafct = f->func.cxa.fn; + arg = f->func.cxa.arg; #ifdef PTR_DEMANGLE PTR_DEMANGLE (cxafct); #endif - cxafct (f->func.cxa.arg, status); + /* Unlock the list while we call a foreign function. */ + __libc_lock_unlock (__exit_funcs_lock); + cxafct (arg, status); + __libc_lock_lock (__exit_funcs_lock); break; } - /* Re-lock again before looking at global state. */ - __libc_lock_lock (__exit_funcs_lock); if (__glibc_unlikely (new_exitfn_called != __new_exitfn_called)) /* The last exit function, or another thread, has registered @@ -123,9 +130,10 @@ __run_exit_handlers (int status, struct exit_function_list **listp, allocate element. */ free (cur); - __libc_lock_unlock (__exit_funcs_lock); } + __libc_lock_unlock (__exit_funcs_lock); + if (run_list_atexit) RUN_HOOK (__libc_atexit, ()); diff --git a/stdlib/test-cxa_atexit-race2.c b/stdlib/test-cxa_atexit-race2.c new file mode 100644 index 0000000000..27f142c6a3 --- /dev/null +++ b/stdlib/test-cxa_atexit-race2.c @@ -0,0 +1,114 @@ +/* Support file for atexit/exit, etc. race tests. + Copyright (C) 2017-2021 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 + . */ + +/* This file must be run from within a directory called "stdlib". */ + +/* The atexit/exit, at_quick_exit/quick_exit, __cxa_atexit/exit, etc. exhibited + data race while calling destructors. + + This test registers destructors from the background thread, and checks that + the same destructor is not called more than once. */ + +#include +#include +#include +#include +#include +#include + +static atomic_int registered; +static atomic_int todo = 100000; + +static void +atexit_cb (void *arg) +{ + atomic_fetch_sub (®istered, 1); + static void *prev; + if (arg == prev) + { + printf ("%p\n", arg); + abort (); + } + prev = arg; + + while (atomic_load (&todo) > 0 && atomic_load (®istered) < 100) + ; +} + +int __cxa_atexit (void (*func) (void *), void *arg, void *d); + +static void *cb_arg = NULL; +static void +add_handlers (void) +{ + int n = 10; + for (int i = 0; i < n; ++i) + __cxa_atexit (&atexit_cb, ++cb_arg, 0); + atomic_fetch_add (®istered, n); + atomic_fetch_sub (&todo, n); +} + +static void * +thread_func (void *arg) +{ + while (atomic_load (&todo) > 0) + if (atomic_load (®istered) < 10000) + add_handlers (); + return 0; +} + +static void +test_and_exit (void) +{ + pthread_attr_t attr; + + xpthread_attr_init (&attr); + xpthread_attr_setdetachstate (&attr, 1); + + xpthread_create (&attr, thread_func, NULL); + xpthread_attr_destroy (&attr); + while (!atomic_load (®istered)) + ; + exit (0); +} + +static int +do_test (void) +{ + for (int i = 0; i < 20; ++i) + { + for (int i = 0; i < 10; ++i) + if (fork () == 0) + test_and_exit (); + + int status; + while (wait (&status) > 0) + { + if (!WIFEXITED (status)) + { + printf ("Failed interation %d\n", i); + abort (); + } + } + } + + exit (0); +} + +#define TEST_FUNCTION do_test +#include