From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 42F1D11C86 for ; Mon, 24 Jul 2023 21:35:16 +0000 (UTC) Received: from smtp-fw-9103.amazon.com (smtp-fw-9103.amazon.com [207.171.188.200]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ECB40D8 for ; Mon, 24 Jul 2023 14:35:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1690234514; x=1721770514; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=hcvQNZkvfX2vFau8D+np+b9z7pYGBCs+SMJJs1BvtQE=; b=aWBft0lls+/8jb504AUuTaMKWqDNkJ+TpEJsjyUdWxDpGEpFVOIe1Fv1 JsdUjGJ0bddGgpjUZhfsGwnOHUXGkPsuRwS0XCaEeqWhO4vvt1qE+mp1A R8NKPAN6Js2TIv/za3Yqc8O2n4BNAzmZDsZOeAPknNAV/0rzupaMye+y/ I=; X-IronPort-AV: E=Sophos;i="6.01,228,1684800000"; d="scan'208";a="1144782005" Received: from pdx4-co-svc-p1-lb2-vlan3.amazon.com (HELO email-inbound-relay-pdx-2c-m6i4x-f7c754c9.us-west-2.amazon.com) ([10.25.36.214]) by smtp-border-fw-9103.sea19.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Jul 2023 21:35:07 +0000 Received: from EX19MTAUWB002.ant.amazon.com (pdx1-ws-svc-p6-lb9-vlan2.pdx.amazon.com [10.236.137.194]) by email-inbound-relay-pdx-2c-m6i4x-f7c754c9.us-west-2.amazon.com (Postfix) with ESMTPS id E392240DB7; Mon, 24 Jul 2023 21:35:04 +0000 (UTC) Received: from EX19D004ANA001.ant.amazon.com (10.37.240.138) by EX19MTAUWB002.ant.amazon.com (10.250.64.231) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.30; Mon, 24 Jul 2023 21:35:04 +0000 Received: from 88665a182662.ant.amazon.com (10.106.100.36) by EX19D004ANA001.ant.amazon.com (10.37.240.138) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.30; Mon, 24 Jul 2023 21:35:00 +0000 From: Kuniyuki Iwashima To: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni CC: Willem de Bruijn , Kees Cook , "Gustavo A. R. Silva" , "Breno Leitao" , Kuniyuki Iwashima , "Kuniyuki Iwashima" , , syzkaller Subject: [PATCH v3 net 1/2] af_unix: Fix fortify_panic() in unix_bind_bsd(). Date: Mon, 24 Jul 2023 14:34:24 -0700 Message-ID: <20230724213425.22920-2-kuniyu@amazon.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20230724213425.22920-1-kuniyu@amazon.com> References: <20230724213425.22920-1-kuniyu@amazon.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.106.100.36] X-ClientProxiedBy: EX19D040UWA002.ant.amazon.com (10.13.139.113) To EX19D004ANA001.ant.amazon.com (10.37.240.138) Precedence: Bulk X-Spam-Status: No, score=-4.0 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_MED,RCVD_IN_MSPIKE_H5,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE, T_SCC_BODY_TEXT_LINE,T_SPF_PERMERROR autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net syzkaller found a bug in unix_bind_bsd() [0]. We can reproduce it by bind()ing a socket on a path with length 108. 108 is the size of sun_addr of struct sockaddr_un and is the maximum valid length for the pathname socket. When calling bind(), we use struct sockaddr_storage as the actual buffer size, so terminating sun_addr[108] with null is legitimate as done in unix_mkname_bsd(). However, strlen(sunaddr) for such a case causes fortify_panic() if CONFIG_FORTIFY_SOURCE=y. __fortify_strlen() has no idea about the actual buffer size and see the string as unterminated. Let's use strnlen() to allow sun_addr to be unterminated at 107. [0]: detected buffer overflow in __fortify_strlen kernel BUG at lib/string_helpers.c:1031! Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP Modules linked in: CPU: 0 PID: 255 Comm: syz-executor296 Not tainted 6.5.0-rc1-00330-g60cc1f7d0605 #4 Hardware name: linux,dummy-virt (DT) pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : fortify_panic+0x1c/0x20 lib/string_helpers.c:1030 lr : fortify_panic+0x1c/0x20 lib/string_helpers.c:1030 sp : ffff800089817af0 x29: ffff800089817af0 x28: ffff800089817b40 x27: 1ffff00011302f68 x26: 000000000000006e x25: 0000000000000012 x24: ffff800087e60140 x23: dfff800000000000 x22: ffff800089817c20 x21: ffff800089817c8e x20: 000000000000006c x19: ffff00000c323900 x18: ffff800086ab1630 x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000001 x14: 1ffff00011302eb8 x13: 0000000000000000 x12: 0000000000000000 x11: 0000000000000000 x10: 0000000000000000 x9 : 64a26b65474d2a00 x8 : 64a26b65474d2a00 x7 : 0000000000000001 x6 : 0000000000000001 x5 : ffff800089817438 x4 : ffff800086ac99e0 x3 : ffff800080f19e8c x2 : 0000000000000001 x1 : 0000000100000000 x0 : 000000000000002c Call trace: fortify_panic+0x1c/0x20 lib/string_helpers.c:1030 _Z16__fortify_strlenPKcU25pass_dynamic_object_size1 include/linux/fortify-string.h:217 [inline] unix_bind_bsd net/unix/af_unix.c:1212 [inline] unix_bind+0xba8/0xc58 net/unix/af_unix.c:1326 __sys_bind+0x1ac/0x248 net/socket.c:1792 __do_sys_bind net/socket.c:1803 [inline] __se_sys_bind net/socket.c:1801 [inline] __arm64_sys_bind+0x7c/0x94 net/socket.c:1801 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x134/0x240 arch/arm64/kernel/syscall.c:139 do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:188 el0_svc+0x2c/0x7c arch/arm64/kernel/entry-common.c:647 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:665 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591 Code: aa0003e1 d0000e80 91030000 97ffc91a (d4210000) Fixes: df8fc4e934c1 ("kbuild: Enable -fstrict-flex-arrays=3") Reported-by: syzkaller Suggested-by: Kees Cook Signed-off-by: Kuniyuki Iwashima --- net/unix/af_unix.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 123b35ddfd71..bbacf4c60fe3 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1208,10 +1208,8 @@ static int unix_bind_bsd(struct sock *sk, struct sockaddr_un *sunaddr, struct path parent; int err; - unix_mkname_bsd(sunaddr, addr_len); - addr_len = strlen(sunaddr->sun_path) + - offsetof(struct sockaddr_un, sun_path) + 1; - + addr_len = strnlen(sunaddr->sun_path, sizeof(sunaddr->sun_path)) + + offsetof(struct sockaddr_un, sun_path) + 1; addr = unix_create_addr(sunaddr, addr_len); if (!addr) return -ENOMEM; -- 2.30.2