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Thu, 24 Dec 2020 07:17:13 -0800 (PST) To: libc-alpha@sourceware.org, Paul Eggert Subject: [PATCH 4/5] stdlib: Add testcase fro BZ #26241 Date: Thu, 24 Dec 2020 12:17:00 -0300 Message-Id: <20201224151701.1751008-5-adhemerval.zanella@linaro.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20201224151701.1751008-1-adhemerval.zanella@linaro.org> References: <20201224151701.1751008-1-adhemerval.zanella@linaro.org> MIME-Version: 1.0 X-Spam-Status: No, score=-13.4 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, KAM_NUMSUBJECT, KAM_SHORT, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Adhemerval Zanella via Libc-alpha From: Adhemerval Zanella Reply-To: Adhemerval Zanella Cc: bug-gnulib@gnu.org Errors-To: libc-alpha-bounces@sourceware.org Sender: "Libc-alpha" Checked on x86_64-linux-gnu and i686-linux-gnu. --- stdlib/Makefile | 3 +- stdlib/tst-canon-bz26341.c | 108 ++++++++++++++++++ support/support_set_small_thread_stack_size.c | 12 +- support/xthread.h | 2 + 4 files changed, 121 insertions(+), 4 deletions(-) create mode 100644 stdlib/tst-canon-bz26341.c diff --git a/stdlib/Makefile b/stdlib/Makefile index 29b7cd7071..6518d8993b 100644 --- a/stdlib/Makefile +++ b/stdlib/Makefile @@ -86,7 +86,7 @@ tests := tst-strtol tst-strtod testmb testrand testsort testdiv \ tst-makecontext-align test-bz22786 tst-strtod-nan-sign \ tst-swapcontext1 tst-setcontext4 tst-setcontext5 \ tst-setcontext6 tst-setcontext7 tst-setcontext8 \ - tst-setcontext9 tst-bz20544 + tst-setcontext9 tst-bz20544 tst-canon-bz26341 tests-internal := tst-strtod1i tst-strtod3 tst-strtod4 tst-strtod5i \ tst-tls-atexit tst-tls-atexit-nodelete @@ -101,6 +101,7 @@ 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-on_exit-race = $(shared-thread-library) +LDLIBS-tst-canon-bz26341 = $(shared-thread-library) LDLIBS-test-dlclose-exit-race = $(shared-thread-library) $(libdl) LDFLAGS-test-dlclose-exit-race = $(LDFLAGS-rdynamic) diff --git a/stdlib/tst-canon-bz26341.c b/stdlib/tst-canon-bz26341.c new file mode 100644 index 0000000000..63474bddaa --- /dev/null +++ b/stdlib/tst-canon-bz26341.c @@ -0,0 +1,108 @@ +/* Check if realpath does not consume extra stack space based on symlink + existance in the path (BZ #26341) + Copyright (C) 2020 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 + . */ + +#include +#include +#include + +#include +#include +#include +#include +#include + +static char *filename; +static size_t filenamelen; +static char *linkname; + +static int +maxsymlinks (void) +{ +#ifdef MAXSYMLINKS + return MAXSYMLINKS; +#else + long int sysconf_symloop_max = sysconf (_SC_SYMLOOP_MAX); + return sysconf_symloop_max <= 0 + ? _POSIX_SYMLOOP_MAX + : sysconf_symloop_max; +#endif +} + +#ifndef PATH_MAX +# define PATH_MAX 1024 +#endif + +static void +create_link (void) +{ + int fd = create_temp_file ("tst-canon-bz26341", &filename); + TEST_VERIFY_EXIT (fd != -1); + xclose (fd); + + char *prevlink = filename; + int maxlinks = maxsymlinks (); + for (int i = 0; i < maxlinks; i++) + { + linkname = xasprintf ("%s%d", filename, i); + xsymlink (prevlink, linkname); + add_temp_file (linkname); + prevlink = linkname; + } + + filenamelen = strlen (filename); +} + +static void * +do_realpath (void *arg) +{ + /* Old implementation of realpath allocates a PATH_MAX using alloca + for each symlink in the path, leading to MAXSYMLINKS times PATH_MAX + maximum stack usage. + This stack allocations tries fill the thread allocated stack minus + both the thread (plus some slack) and the realpath (plus some slack). + If realpath uses more than 2 * PATH_MAX plus some slack it will trigger + a stackoverflow. */ + + const size_t realpath_usage = 2 * PATH_MAX + 1024; + const size_t thread_usage = 1 * PATH_MAX + 1024; + size_t stack_size = support_small_thread_stack_size () + - realpath_usage - thread_usage; + char stack[stack_size]; + char *resolved = stack + stack_size - thread_usage + 1024; + + char *p = realpath (linkname, resolved); + TEST_VERIFY (p != NULL); + TEST_COMPARE_BLOB (resolved, filenamelen, filename, filenamelen); + + return NULL; +} + +static int +do_test (void) +{ + create_link (); + + pthread_t th = xpthread_create (support_small_stack_thread_attribute (), + do_realpath, NULL); + xpthread_join (th); + + return 0; +} + +#include diff --git a/support/support_set_small_thread_stack_size.c b/support/support_set_small_thread_stack_size.c index 69d66e97db..74a0e38a72 100644 --- a/support/support_set_small_thread_stack_size.c +++ b/support/support_set_small_thread_stack_size.c @@ -20,8 +20,8 @@ #include #include -void -support_set_small_thread_stack_size (pthread_attr_t *attr) +size_t +support_small_thread_stack_size (void) { /* Some architectures have too small values for PTHREAD_STACK_MIN which cannot be used for creating threads. Ensure that the stack @@ -31,5 +31,11 @@ support_set_small_thread_stack_size (pthread_attr_t *attr) if (stack_size < PTHREAD_STACK_MIN) stack_size = PTHREAD_STACK_MIN; #endif - xpthread_attr_setstacksize (attr, stack_size); + return stack_size; +} + +void +support_set_small_thread_stack_size (pthread_attr_t *attr) +{ + xpthread_attr_setstacksize (attr, support_small_thread_stack_size ()); } diff --git a/support/xthread.h b/support/xthread.h index 05f8d4a7d9..6ba2f5a18b 100644 --- a/support/xthread.h +++ b/support/xthread.h @@ -78,6 +78,8 @@ void xpthread_attr_setguardsize (pthread_attr_t *attr, /* Set the stack size in ATTR to a small value, but still large enough to cover most internal glibc stack usage. */ void support_set_small_thread_stack_size (pthread_attr_t *attr); +/* Return the stack size used on support_set_small_thread_stack_size. */ +size_t support_small_thread_stack_size (void); /* Return a pointer to a thread attribute which requests a small stack. The caller must not free this pointer. */