From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cheetah.ash.relay.mailchannels.net (cheetah.ash.relay.mailchannels.net [23.83.222.34]) by sourceware.org (Postfix) with ESMTPS id 30ED53858409 for ; Mon, 24 Jan 2022 06:51:02 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 30ED53858409 X-Sender-Id: dreamhost|x-authsender|siddhesh@gotplt.org Received: from relay.mailchannels.net (localhost [127.0.0.1]) by relay.mailchannels.net (Postfix) with ESMTP id CFA606C1471; Mon, 24 Jan 2022 06:50:59 +0000 (UTC) Received: from pdx1-sub0-mail-a305.dreamhost.com (unknown [127.0.0.6]) (Authenticated sender: dreamhost) by relay.mailchannels.net (Postfix) with ESMTPA id 1727A6C1B38; Mon, 24 Jan 2022 06:50:59 +0000 (UTC) X-Sender-Id: dreamhost|x-authsender|siddhesh@gotplt.org Received: from pdx1-sub0-mail-a305.dreamhost.com (pop.dreamhost.com [64.90.62.162]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384) by 100.114.196.241 (trex/6.4.3); Mon, 24 Jan 2022 06:50:59 +0000 X-MC-Relay: Neutral X-MailChannels-SenderId: dreamhost|x-authsender|siddhesh@gotplt.org X-MailChannels-Auth-Id: dreamhost X-Whistle-Chief: 7253df300d2a814c_1643007059337_2715105825 X-MC-Loop-Signature: 1643007059337:3897004146 X-MC-Ingress-Time: 1643007059337 Received: from rhbox.redhat.com (unknown [1.186.122.50]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: siddhesh@gotplt.org) by pdx1-sub0-mail-a305.dreamhost.com (Postfix) with ESMTPSA id 4Jj0xY3yTWz1b; Sun, 23 Jan 2022 22:50:57 -0800 (PST) From: Siddhesh Poyarekar To: libc-stable@sourceware.org Subject: [committed 2.34 4/6] realpath: Set errno to ENAMETOOLONG for result larger than PATH_MAX [BZ #28770] Date: Mon, 24 Jan 2022 12:20:40 +0530 Message-Id: <20220124065042.3497514-5-siddhesh@sourceware.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220124065042.3497514-1-siddhesh@sourceware.org> References: <20220124065042.3497514-1-siddhesh@sourceware.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-3494.3 required=5.0 tests=BAYES_00, GIT_PATCH_0, JMQ_SPF_NEUTRAL, KAM_DMARC_NONE, KAM_DMARC_STATUS, KAM_SHORT, RCVD_IN_BARRACUDACENTRAL, RCVD_IN_DNSWL_NONE, RCVD_IN_SBL, SPF_HELO_NONE, SPF_NEUTRAL, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libc-stable@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-stable mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 24 Jan 2022 06:51:06 -0000 realpath returns an allocated string when the result exceeds PATH_MAX, which is unexpected when its second argument is not NULL. This results in the second argument (resolved) being uninitialized and also results in a memory leak since the caller expects resolved to be the same as the returned value. Return NULL and set errno to ENAMETOOLONG if the result exceeds PATH_MAX. This fixes [BZ #28770], which is CVE-2021-3998. Reviewed-by: Adhemerval Zanella Signed-off-by: Siddhesh Poyarekar (cherry picked from commit ee8d5e33adb284601c00c94687bc907e10aec9bb) --- NEWS | 4 +++ stdlib/Makefile | 1 + stdlib/canonicalize.c | 12 +++++++-- stdlib/tst-realpath-toolong.c | 49 +++++++++++++++++++++++++++++++++++ 4 files changed, 64 insertions(+), 2 deletions(-) create mode 100644 stdlib/tst-realpath-toolong.c diff --git a/NEWS b/NEWS index 7e773bd005..b4f81c2668 100644 --- a/NEWS +++ b/NEWS @@ -16,6 +16,10 @@ Security related changes: CVE-2022-23218: Passing an overlong file name to the svcunix_create legacy function could result in a stack-based buffer overflow. + CVE-2021-3998: Passing a path longer than PATH_MAX to the realpath + function could result in a memory leak and potential access of + uninitialized memory. Reported by Qualys. + The following bugs are resolved with this release: [12889] nptl: Fix race between pthread_kill and thread exit diff --git a/stdlib/Makefile b/stdlib/Makefile index 9bb5c221e8..a4ac30d1f6 100644 --- a/stdlib/Makefile +++ b/stdlib/Makefile @@ -109,6 +109,7 @@ tests := \ tst-random \ tst-random2 \ tst-realpath \ + tst-realpath-toolong \ tst-secure-getenv \ tst-setcontext \ tst-setcontext2 \ diff --git a/stdlib/canonicalize.c b/stdlib/canonicalize.c index 698f9ede25..7a23a51b3a 100644 --- a/stdlib/canonicalize.c +++ b/stdlib/canonicalize.c @@ -400,8 +400,16 @@ realpath_stk (const char *name, char *resolved, error: *dest++ = '\0'; - if (resolved != NULL && dest - rname <= get_path_max ()) - rname = strcpy (resolved, rname); + if (resolved != NULL) + { + if (dest - rname <= get_path_max ()) + rname = strcpy (resolved, rname); + else + { + failed = true; + __set_errno (ENAMETOOLONG); + } + } error_nomem: scratch_buffer_free (&extra_buffer); diff --git a/stdlib/tst-realpath-toolong.c b/stdlib/tst-realpath-toolong.c new file mode 100644 index 0000000000..8bed772460 --- /dev/null +++ b/stdlib/tst-realpath-toolong.c @@ -0,0 +1,49 @@ +/* Verify that realpath returns NULL with ENAMETOOLONG if the result exceeds + NAME_MAX. + Copyright The GNU Toolchain Authors. + 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 +#include + +#define BASENAME "tst-realpath-toolong." + +int +do_test (void) +{ + char *base = support_create_and_chdir_toolong_temp_directory (BASENAME); + + char buf[PATH_MAX + 1]; + const char *res = realpath (".", buf); + + /* canonicalize.c states that if the real path is >= PATH_MAX, then + realpath returns NULL and sets ENAMETOOLONG. */ + TEST_VERIFY (res == NULL); + TEST_VERIFY (errno == ENAMETOOLONG); + + free (base); + return 0; +} + +#include -- 2.34.1