From patchwork Thu Jul 20 00:44:09 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kuniyuki Iwashima X-Patchwork-Id: 13319667 X-Patchwork-Delegate: kuba@kernel.org 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 40173621 for ; Thu, 20 Jul 2023 00:45:17 +0000 (UTC) Received: from smtp-fw-52005.amazon.com (smtp-fw-52005.amazon.com [52.119.213.156]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A41912100 for ; Wed, 19 Jul 2023 17:45:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1689813917; x=1721349917; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=ilr1spx6x8Sja/x4OJeBwc7Btf7Qagl8uMdd/OqmKW8=; b=q8CfgbvMfJEi28dHZ2bDEyFxyGTzex916pod5jEkeCBFbgCkTcyL4apb EeFd66sFBBPUZRLqktxaYu3oNTYHorMSVZiE9vPk2t7i0wZh45i+r8gdZ FAkQuMN9siyXrTGiXaXNRCe3tj9IyYcysBKlzq/oFmFdHkk4wF1qUw9Ax I=; X-IronPort-AV: E=Sophos;i="6.01,216,1684800000"; d="scan'208";a="593943980" Received: from iad12-co-svc-p1-lb1-vlan3.amazon.com (HELO email-inbound-relay-iad-1a-m6i4x-bbc6e425.us-east-1.amazon.com) ([10.43.8.6]) by smtp-border-fw-52005.iad7.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Jul 2023 00:45:15 +0000 Received: from EX19MTAUWC002.ant.amazon.com (iad12-ws-svc-p26-lb9-vlan3.iad.amazon.com [10.40.163.38]) by email-inbound-relay-iad-1a-m6i4x-bbc6e425.us-east-1.amazon.com (Postfix) with ESMTPS id E79AE8059C; Thu, 20 Jul 2023 00:45:11 +0000 (UTC) Received: from EX19D004ANA001.ant.amazon.com (10.37.240.138) by EX19MTAUWC002.ant.amazon.com (10.250.64.143) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.30; Thu, 20 Jul 2023 00:45:11 +0000 Received: from 88665a182662.ant.amazon.com (10.106.101.39) 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; Thu, 20 Jul 2023 00:45:07 +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 , Willem de Bruijn Subject: [PATCH v2 net 1/2] af_unix: Fix fortify_panic() in unix_bind_bsd(). Date: Wed, 19 Jul 2023 17:44:09 -0700 Message-ID: <20230720004410.87588-2-kuniyu@amazon.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20230720004410.87588-1-kuniyu@amazon.com> References: <20230720004410.87588-1-kuniyu@amazon.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Originating-IP: [10.106.101.39] X-ClientProxiedBy: EX19D038UWC001.ant.amazon.com (10.13.139.213) To EX19D004ANA001.ant.amazon.com (10.37.240.138) Precedence: Bulk X-Spam-Status: No, score=-1.7 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_BLOCKED,RCVD_IN_MSPIKE_H5,RCVD_IN_MSPIKE_WL, SPF_HELO_NONE,T_SCC_BODY_TEXT_LINE,T_SPF_PERMERROR autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net X-Patchwork-Delegate: kuba@kernel.org 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. 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 takes 108 as overflow, although 108 still fits in struct sockaddr_storage. Let's make __fortify_strlen() recognise the actual buffer size. [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 Signed-off-by: Kuniyuki Iwashima Reviewed-by: Willem de Bruijn --- net/unix/af_unix.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 123b35ddfd71..e1b1819b96d1 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -302,6 +302,18 @@ static void unix_mkname_bsd(struct sockaddr_un *sunaddr, int addr_len) ((char *)sunaddr)[addr_len] = 0; } +static int unix_strlen_bsd(struct sockaddr_un *sunaddr) +{ + /* Don't pass sunaddr->sun_path to strlen(). Otherwise, the + * max valid length UNIX_PATH_MAX (108) will cause panic if + * CONFIG_FORTIFY_SOURCE=y. Let __fortify_strlen() know that + * the actual buffer is struct sockaddr_storage and that 108 + * is within __data[]. See also: unix_mkname_bsd(). + */ + return strlen(((struct sockaddr_storage *)sunaddr)->__data) + + offsetof(struct sockaddr_un, sun_path) + 1; +} + static void __unix_remove_socket(struct sock *sk) { sk_del_node_init(sk); @@ -1209,9 +1221,7 @@ static int unix_bind_bsd(struct sock *sk, struct sockaddr_un *sunaddr, int err; unix_mkname_bsd(sunaddr, addr_len); - addr_len = strlen(sunaddr->sun_path) + - offsetof(struct sockaddr_un, sun_path) + 1; - + addr_len = unix_strlen_bsd(sunaddr); addr = unix_create_addr(sunaddr, addr_len); if (!addr) return -ENOMEM;