From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dormouse.elm.relay.mailchannels.net (dormouse.elm.relay.mailchannels.net [23.83.212.50]) by sourceware.org (Postfix) with ESMTPS id 4ABDB3861C76 for ; Tue, 3 Oct 2023 17:08:48 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 4ABDB3861C76 Authentication-Results: sourceware.org; dmarc=fail (p=none dis=none) header.from=sourceware.org Authentication-Results: sourceware.org; spf=fail smtp.mailfrom=sourceware.org 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 0769882118; Tue, 3 Oct 2023 17:08:47 +0000 (UTC) Received: from pdx1-sub0-mail-a208.dreamhost.com (unknown [127.0.0.6]) (Authenticated sender: dreamhost) by relay.mailchannels.net (Postfix) with ESMTPA id 99FD4812EC; Tue, 3 Oct 2023 17:08:46 +0000 (UTC) ARC-Seal: i=1; s=arc-2022; d=mailchannels.net; t=1696352926; a=rsa-sha256; cv=none; b=c8QwSg7AP0/z5Aj0uf1fFvu8wYJcq2fsbQEPkOtc+szCmsGiI6omKn6bJsBuS+ESEECnM/ HNoAJFw+m0IEA/1IyziOuM6eAYowaHA9OJe5SnNAPtPScGkYjyLo7j1qq/rku+uTVccxyi JeC+6bMqqq6g3m3f+t03WpJn1tVd9ZL9hMR90I+DL6DtEnaeWaeWYqGz30WcUB5Nj3RdOB uVPWFR1a/EjJg/AIakchBc1/BIvw/EtXSLbB6pU5Xjaf2p+kT/C7t3Jah9KhQ5pif+GE4f 3EYBmEJ+FPSXKAVSq2A6mzZBR4+uWJH3oU7LBWsDlTjYEOFhSNfk8B0BdF2Rcg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=mailchannels.net; s=arc-2022; t=1696352926; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Ejo9FGuaeTz9tnS79uQ7kOQk/h/m9poTqLEioPUx28c=; b=4ACaGslYChggW/k7yfUMdG2bCCSeVnyZjfbIZvVUm8AWkRGQ0wl8W2QEGMnYNKKddy2pHw fdP9Z0Cay4WmW6HTNCBnrHgdeGg5pNA7TBq4n0EWHjg0WG/mVFF7PGrpGrZxTeqdQLamba 8WhvBixvFD0LYmDjfiCmtdlUbHa3lsVahI/fsRVeEvI9uVCeQwPgKZPUNZSfyebSqpM0cN jEln32L42K/qzpyMIxUm1DLSND8N5rvbsYOEtfVtRQGRzOjmbCj73jNuZ1YlXWn/FiK1Gy jDPiSuWbKp3+XlBonQ6/4IYkjmKkZzVx/j/fUHIlw0AQKBoijGdx17GJp/TlWw== ARC-Authentication-Results: i=1; rspamd-7d5dc8fd68-wbd6g; auth=pass smtp.auth=dreamhost smtp.mailfrom=siddhesh@sourceware.org X-Sender-Id: dreamhost|x-authsender|siddhesh@gotplt.org X-MC-Relay: Neutral X-MC-Copy: stored-urls X-MailChannels-SenderId: dreamhost|x-authsender|siddhesh@gotplt.org X-MailChannels-Auth-Id: dreamhost X-Trail-White: 04266fc31da796f7_1696352926864_2895641074 X-MC-Loop-Signature: 1696352926864:1384058374 X-MC-Ingress-Time: 1696352926864 Received: from pdx1-sub0-mail-a208.dreamhost.com (pop.dreamhost.com [64.90.62.162]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384) by 100.109.110.212 (trex/6.9.1); Tue, 03 Oct 2023 17:08:46 +0000 Received: from fedora.redhat.com (bras-vprn-toroon4834w-lp130-02-142-113-138-41.dsl.bell.ca [142.113.138.41]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: siddhesh@gotplt.org) by pdx1-sub0-mail-a208.dreamhost.com (Postfix) with ESMTPSA id 4S0PRf1TfVz11L; Tue, 3 Oct 2023 10:08:46 -0700 (PDT) From: Siddhesh Poyarekar To: libc-stable@sourceware.org Cc: Carlos O'Donell Subject: [committed 2.36] tunables: Terminate if end of input is reached (CVE-2023-4911) Date: Tue, 3 Oct 2023 13:08:35 -0400 Message-ID: <20231003170837.64992-5-siddhesh@sourceware.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20231003170837.64992-1-siddhesh@sourceware.org> References: <20231003170837.64992-1-siddhesh@sourceware.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-1172.5 required=5.0 tests=BAYES_00,GIT_PATCH_0,KAM_DMARC_NONE,KAM_DMARC_STATUS,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_SOFTFAIL,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: The string parsing routine may end up writing beyond bounds of tunestr if the input tunable string is malformed, of the form name=name=val. This gets processed twice, first as name=name=val and next as name=val, resulting in tunestr being name=name=val:name=val, thus overflowing tunestr. Terminate the parsing loop at the first instance itself so that tunestr does not overflow. This also fixes up tst-env-setuid-tunables to actually handle failures correct and add new tests to validate the fix for this CVE. Signed-off-by: Siddhesh Poyarekar Reviewed-by: Carlos O'Donell (cherry picked from commit 1056e5b4c3f2d90ed2b4a55f96add28da2f4c8fa) --- NEWS | 5 +++++ elf/dl-tunables.c | 17 +++++++++------- elf/tst-env-setuid-tunables.c | 37 +++++++++++++++++++++++++++-------- 3 files changed, 44 insertions(+), 15 deletions(-) diff --git a/NEWS b/NEWS index ae55ffb53a..5358e0cbe3 100644 --- a/NEWS +++ b/NEWS @@ -36,6 +36,11 @@ Security related changes: an application calls getaddrinfo for AF_INET6 with AI_CANONNAME, AI_ALL and AI_V4MAPPED flags set. + CVE-2023-4911: If a tunable of the form NAME=NAME=VAL is passed in the + environment of a setuid program and NAME is valid, it may result in a + buffer overflow, which could be exploited to achieve escalated + privileges. This flaw was introduced in glibc 2.34. + The following bugs are resolved with this release: [12154] Do not fail DNS resolution for CNAMEs which are not host names diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c index 8e7ee9df10..76cf8b9da3 100644 --- a/elf/dl-tunables.c +++ b/elf/dl-tunables.c @@ -187,11 +187,7 @@ parse_tunables (char *tunestr, char *valstring) /* If we reach the end of the string before getting a valid name-value pair, bail out. */ if (p[len] == '\0') - { - if (__libc_enable_secure) - tunestr[off] = '\0'; - return; - } + break; /* We did not find a valid name-value pair before encountering the colon. */ @@ -251,9 +247,16 @@ parse_tunables (char *tunestr, char *valstring) } } - if (p[len] != '\0') - p += len + 1; + /* We reached the end while processing the tunable string. */ + if (p[len] == '\0') + break; + + p += len + 1; } + + /* Terminate tunestr before we leave. */ + if (__libc_enable_secure) + tunestr[off] = '\0'; } #endif diff --git a/elf/tst-env-setuid-tunables.c b/elf/tst-env-setuid-tunables.c index 88182b7b25..5e9e4c5756 100644 --- a/elf/tst-env-setuid-tunables.c +++ b/elf/tst-env-setuid-tunables.c @@ -52,6 +52,8 @@ const char *teststrings[] = "glibc.malloc.perturb=0x800:not_valid.malloc.check=2:glibc.malloc.mmap_threshold=4096", "glibc.not_valid.check=2:glibc.malloc.mmap_threshold=4096", "not_valid.malloc.check=2:glibc.malloc.mmap_threshold=4096", + "glibc.malloc.mmap_threshold=glibc.malloc.mmap_threshold=4096", + "glibc.malloc.check=2", "glibc.malloc.garbage=2:glibc.maoc.mmap_threshold=4096:glibc.malloc.check=2", "glibc.malloc.check=4:glibc.malloc.garbage=2:glibc.maoc.mmap_threshold=4096", ":glibc.malloc.garbage=2:glibc.malloc.check=1", @@ -70,6 +72,8 @@ const char *resultstrings[] = "glibc.malloc.perturb=0x800:glibc.malloc.mmap_threshold=4096", "glibc.malloc.mmap_threshold=4096", "glibc.malloc.mmap_threshold=4096", + "glibc.malloc.mmap_threshold=glibc.malloc.mmap_threshold=4096", + "", "", "", "", @@ -84,11 +88,18 @@ test_child (int off) const char *val = getenv ("GLIBC_TUNABLES"); #if HAVE_TUNABLES + printf (" [%d] GLIBC_TUNABLES is %s\n", off, val); + fflush (stdout); if (val != NULL && strcmp (val, resultstrings[off]) == 0) return 0; if (val != NULL) - printf ("[%d] Unexpected GLIBC_TUNABLES VALUE %s\n", off, val); + printf (" [%d] Unexpected GLIBC_TUNABLES VALUE %s, expected %s\n", + off, val, resultstrings[off]); + else + printf (" [%d] GLIBC_TUNABLES environment variable absent\n", off); + + fflush (stdout); return 1; #else @@ -117,21 +128,26 @@ do_test (int argc, char **argv) if (ret != 0) exit (1); - exit (EXIT_SUCCESS); + /* Special return code to make sure that the child executed all the way + through. */ + exit (42); } else { - int ret = 0; - /* Spawn tests. */ for (int i = 0; i < array_length (teststrings); i++) { char buf[INT_BUFSIZE_BOUND (int)]; - printf ("Spawned test for %s (%d)\n", teststrings[i], i); + printf ("[%d] Spawned test for %s\n", i, teststrings[i]); snprintf (buf, sizeof (buf), "%d\n", i); + fflush (stdout); if (setenv ("GLIBC_TUNABLES", teststrings[i], 1) != 0) - exit (1); + { + printf (" [%d] Failed to set GLIBC_TUNABLES: %m", i); + support_record_failure (); + continue; + } int status = support_capture_subprogram_self_sgid (buf); @@ -139,9 +155,14 @@ do_test (int argc, char **argv) if (WEXITSTATUS (status) == EXIT_UNSUPPORTED) return EXIT_UNSUPPORTED; - ret |= status; + if (WEXITSTATUS (status) != 42) + { + printf (" [%d] child failed with status %d\n", i, + WEXITSTATUS (status)); + support_record_failure (); + } } - return ret; + return 0; } } -- 2.41.0