From patchwork Wed Nov 25 10:06:59 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xiaoming Ni X-Patchwork-Id: 41185 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id C03BD3958C1E; Wed, 25 Nov 2020 10:08:00 +0000 (GMT) X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from szxga05-in.huawei.com (szxga05-in.huawei.com [45.249.212.191]) by sourceware.org (Postfix) with ESMTPS id 449213955CA6; Wed, 25 Nov 2020 10:07:57 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 449213955CA6 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=nixiaoming@huawei.com Received: from DGGEMS414-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4CgxQK28VBzLv8Q; Wed, 25 Nov 2020 18:07:21 +0800 (CST) Received: from use12-sp2.huawei.com (10.67.189.174) by DGGEMS414-HUB.china.huawei.com (10.3.19.214) with Microsoft SMTP Server id 14.3.487.0; Wed, 25 Nov 2020 18:07:03 +0800 From: Xiaoming Ni To: , , , , , , Subject: [PATCH v4] io:nftw/ftw:fix stack overflow when large nopenfd [BZ #26353] Date: Wed, 25 Nov 2020 18:06:59 +0800 Message-ID: <20201125100659.30923-1-nixiaoming@huawei.com> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 X-Originating-IP: [10.67.189.174] X-CFilter-Loop: Reflected X-Spam-Status: No, score=-13.7 required=5.0 tests=BAYES_00, GIT_PATCH_0, KAM_DMARC_STATUS, KAM_MANYTO, KAM_SHORT, RCVD_IN_MSPIKE_H2, 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: , Cc: wangle6@huawei.com, nixiaoming@huawei.com Errors-To: libc-alpha-bounces@sourceware.org Sender: "Libc-alpha" In ftw_startup(), call alloca to apply for a large amount of stack space. When descriptors is very large, stack overflow is triggered. BZ #26353 Replace the memory application of data.dirstreams from alloca() to malloc() by referring to the memory application of data.dirbuf in the current function. Combine the memory allocation of data.dirbuf and data.dirstreams according to the advice of Adhemerval Zanella. v4: Based on Adhemerval Zanella's review comments, use support_capture_subprocess_check() to rewrite testcase v3: https://public-inbox.org/libc-alpha/20201124131652.111854-1-nixiaoming@huawei.com/ Combine the memory allocation of data.dirbuf and data.dirstreams according to the advice of Adhemerval Zanella. remove the upper limit check of descriptors v2: https://public-inbox.org/libc-alpha/20200815070851.46403-1-nixiaoming@huawei.com/ not set errno after malloc fails. add check ftw return value on testcase add more testcase v1: https://public-inbox.org/libc-alpha/20200808084640.49174-1-nixiaoming@huawei.com/ ' --- io/Makefile | 3 +- io/ftw.c | 16 ++++++----- io/tst-bz26353.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 86 insertions(+), 8 deletions(-) create mode 100644 io/tst-bz26353.c diff --git a/io/Makefile b/io/Makefile index 6dd2c33fcf..7845d07f45 100644 --- a/io/Makefile +++ b/io/Makefile @@ -68,7 +68,8 @@ tests := test-utime test-stat test-stat2 test-lfs tst-getcwd \ tst-posix_fallocate tst-posix_fallocate64 \ tst-fts tst-fts-lfs tst-open-tmpfile \ tst-copy_file_range tst-getcwd-abspath tst-lockf \ - tst-ftw-lnk tst-file_change_detection tst-lchmod + tst-ftw-lnk tst-file_change_detection tst-lchmod \ + tst-bz26353 # Likewise for statx, but we do not need static linking here. tests-internal += tst-statx diff --git a/io/ftw.c b/io/ftw.c index 7104816e85..92e08c5431 100644 --- a/io/ftw.c +++ b/io/ftw.c @@ -646,15 +646,17 @@ ftw_startup (const char *dir, int is_nftw, void *func, int descriptors, data.maxdir = descriptors < 1 ? 1 : descriptors; data.actdir = 0; - data.dirstreams = (struct dir_data **) alloca (data.maxdir - * sizeof (struct dir_data *)); - memset (data.dirstreams, '\0', data.maxdir * sizeof (struct dir_data *)); - /* PATH_MAX is always defined when we get here. */ data.dirbufsize = MAX (2 * strlen (dir), PATH_MAX); - data.dirbuf = (char *) malloc (data.dirbufsize); - if (data.dirbuf == NULL) + data.dirstreams = malloc (data.maxdir * sizeof (struct dir_data *) + + data.dirbufsize); + if (data.dirstreams == NULL) return -1; + + memset (data.dirstreams, '\0', data.maxdir * sizeof (struct dir_data *)); + + data.dirbuf = (char *) data.dirstreams + + data.maxdir * sizeof (struct dir_data *); cp = __stpcpy (data.dirbuf, dir); /* Strip trailing slashes. */ while (cp > data.dirbuf + 1 && cp[-1] == '/') @@ -803,7 +805,7 @@ ftw_startup (const char *dir, int is_nftw, void *func, int descriptors, out_fail: save_err = errno; __tdestroy (data.known_objects, free); - free (data.dirbuf); + free (data.dirstreams); __set_errno (save_err); return result; diff --git a/io/tst-bz26353.c b/io/tst-bz26353.c new file mode 100644 index 0000000000..27f50a8bdc --- /dev/null +++ b/io/tst-bz26353.c @@ -0,0 +1,75 @@ +/* test ftw bz26353: Check whether stack overflow occurs when the value + of the nopenfd parameter is too large. + + 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 int +my_func (const char *file, const struct stat *sb, int flag) +{ + return 0; +} + +static void +do_ftw (void *unused) +{ + char *tempdir = support_create_temp_directory ("tst-bz26353"); + struct rlimit r; + int large_nopenfd = 80 * 1024 * 1024; + int res = getrlimit (RLIMIT_STACK, &r); + if (res == 0) + { + if (r.rlim_cur == RLIM_INFINITY) + { + r.rlim_cur = 8 * 1024 * 1024; + setrlimit (RLIMIT_STACK, &r); + } + large_nopenfd = (int) r.rlim_cur; + } + int ret = ftw (tempdir, my_func, large_nopenfd); + if (ret != 0) + { + printf ("test big num %d, ret=%d errno=%d, without stack overflow\n", + large_nopenfd, ret, errno); + } + free (tempdir); + exit (ret); +} + +/*Check whether stack overflow occurs*/ +static int +do_test (void) +{ + struct support_capture_subprocess result; + result = support_capture_subprocess (do_ftw, NULL); + support_capture_subprocess_check (&result, "bz26353", 0, sc_allow_none); + support_capture_subprocess_free (&result); + return 0; +} + +#include +