From patchwork Sat Jan 21 15:08:59 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hyunwoo Kim X-Patchwork-Id: 13111138 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F333AC25B50 for ; Sat, 21 Jan 2023 15:09:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229790AbjAUPJI (ORCPT ); Sat, 21 Jan 2023 10:09:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44404 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229636AbjAUPJH (ORCPT ); Sat, 21 Jan 2023 10:09:07 -0500 Received: from mail-pf1-x42f.google.com (mail-pf1-x42f.google.com [IPv6:2607:f8b0:4864:20::42f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D4C03233FC for ; Sat, 21 Jan 2023 07:09:05 -0800 (PST) Received: by mail-pf1-x42f.google.com with SMTP id i65so6016694pfc.0 for ; Sat, 21 Jan 2023 07:09:05 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=theori.io; s=google; h=content-disposition:mime-version:message-id:subject:cc:to:from:date :from:to:cc:subject:date:message-id:reply-to; bh=ua+WYyImyb84I3AfuYAXKTbSGe0WmHnzQY8n4YkMLZc=; b=W2qvOd+wCOWXoqtgzqvTlird3EUOe95OfpIbK6PcCwtv+b5Wt4AdI2cgkGBPSFnhtq TvnbqrzY3bzCt+2fTLp9C4nHA/Y/WT7JSOhPrw156sTKxaqo+f314iTt5KsYeylx9VM7 uH7g23Xel3WJxiVrcVt5sEQ/ukFuXIaqX+fp4= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-disposition:mime-version:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=ua+WYyImyb84I3AfuYAXKTbSGe0WmHnzQY8n4YkMLZc=; b=rK42qZy+AxHwdeiqE/YQxVLoYuhBwW6Qdex+Bq6VsQ9KWwI1VUVNkMOwEcWXFG6VcI 4Vfny19p6XcMlVKlIoWLi17Lg5CrGmxE83f6bwtkP6KGOEozeO6SJnuLgh84YnC+/x5H Qw16p1LyQDOaHmI49F9WCCfOoKbNL+1Kq8Xc2WEFlhyFj/MlC709kzebmfS+qsoLrGbw Y84ZxCxZmpI8GAYCTMNpQpiPJD5DWBCzHlf30BYR7YCADj2q0tCjcVbnabhRFpLNXCqm lursB4RSf+yvSSjFPxRKHCAcXAE5hgXsbaEMDGcD5tI4L7S8h/U12nIrucjH7tjl50mi rotA== X-Gm-Message-State: AFqh2kpumLn6RvfyjFUbs/jrwUbT2Ly+1koKzSMwKNrZBf++q0wVJqMz sikHPxTtHKWS8JWwTp3sKuoxVw== X-Google-Smtp-Source: AMrXdXvUFygrv+Ms+mnpUuDtmWeMXzaQGKSUVwVTZZN1j9opOHwvDLR4f9t8XF5XZfi5u6KJxVvI7g== X-Received: by 2002:a62:86c8:0:b0:581:b3f4:21f8 with SMTP id x191-20020a6286c8000000b00581b3f421f8mr11100212pfd.31.1674313745234; Sat, 21 Jan 2023 07:09:05 -0800 (PST) Received: from ubuntu ([39.115.108.115]) by smtp.gmail.com with ESMTPSA id z30-20020aa79e5e000000b0058d97abdefesm12306197pfq.208.2023.01.21.07.09.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 21 Jan 2023 07:09:04 -0800 (PST) Date: Sat, 21 Jan 2023 07:08:59 -0800 From: Hyunwoo Kim To: ralf@linux-mips.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com Cc: v4bel@theori.io, imv4bel@gmail.com, linux-hams@vger.kernel.org, netdev@vger.kernel.org, syzbot+caa188bdfc1eeafeb418@syzkaller.appspotmail.com Subject: [PATCH] netrom: Fix use-after-free caused by accept on already connected socket Message-ID: <20230121150859.GA9817@ubuntu> MIME-Version: 1.0 Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org If listen() and accept() are called on an AF_NETROM socket that has already been connect()ed, accept() succeeds in connecting. This is because nr_accept() dequeues the skb queued in `sk->sk_receive_queue` in nr_connect(). This causes nr_accept() to allocate and return a sock with the sk of the parent AF_NETROM socket. And here's where use-after-free can happen through complex race conditions: ``` cpu0 cpu1 1. socket_2 = socket(AF_NETROM) listen(socket_2) accepted_socket = accept(socket_2) // loopback connection with socket_1 2. socket_1 = socket(AF_NETROM) nr_create() // sk refcount : 1 connect(socket_1) // loopback connection with socket_2 nr_connect() nr_establish_data_link() nr_write_internal() nr_transmit_buffer() nr_route_frame() nr_loopback_queue() nr_loopback_timer() nr_rx_frame() nr_process_rx_frame() nr_state3_machine() nr_queue_rx_frame() sock_queue_rcv_skb() sock_queue_rcv_skb_reason() __sock_queue_rcv_skb() __skb_queue_tail(list, skb); // list : sk->sk_receive_queue 3. listen(socket_1) nr_listen() uaf_socket = accept(socket_1) nr_accept() skb_dequeue(&sk->sk_receive_queue); 4. close(accepted_socket) nr_release() nr_write_internal(sk, NR_DISCREQ) nr_transmit_buffer() // NR_DISCREQ nr_route_frame() nr_loopback_queue() nr_loopback_timer() nr_rx_frame() // sk : socket_1's sk nr_process_rx_frame() // NR_STATE_3 nr_state3_machine() // NR_DISCREQ nr_disconnect() nr_sk(sk)->state = NR_STATE_0; 5. close(socket_1) // sk refcount : 3 nr_release() // NR_STATE_0 sock_put(sk); // sk refcount : 0 sk_free(sk); close(uaf_socket) nr_release() sock_hold(sk); // UAF ``` KASAN report by syzbot: ``` BUG: KASAN: use-after-free in nr_release+0x66/0x460 net/netrom/af_netrom.c:520 Write of size 4 at addr ffff8880235d8080 by task syz-executor564/5128 CPU: 0 PID: 5128 Comm: syz-executor564 Not tainted 6.2.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:306 [inline] print_report+0x15e/0x461 mm/kasan/report.c:417 kasan_report+0xbf/0x1f0 mm/kasan/report.c:517 check_region_inline mm/kasan/generic.c:183 [inline] kasan_check_range+0x141/0x190 mm/kasan/generic.c:189 instrument_atomic_read_write include/linux/instrumented.h:102 [inline] atomic_fetch_add_relaxed include/linux/atomic/atomic-instrumented.h:116 [inline] __refcount_add include/linux/refcount.h:193 [inline] __refcount_inc include/linux/refcount.h:250 [inline] refcount_inc include/linux/refcount.h:267 [inline] sock_hold include/net/sock.h:775 [inline] nr_release+0x66/0x460 net/netrom/af_netrom.c:520 __sock_release+0xcd/0x280 net/socket.c:650 sock_close+0x1c/0x20 net/socket.c:1365 __fput+0x27c/0xa90 fs/file_table.c:320 task_work_run+0x16f/0x270 kernel/task_work.c:179 exit_task_work include/linux/task_work.h:38 [inline] do_exit+0xaa8/0x2950 kernel/exit.c:867 do_group_exit+0xd4/0x2a0 kernel/exit.c:1012 get_signal+0x21c3/0x2450 kernel/signal.c:2859 arch_do_signal_or_restart+0x79/0x5c0 arch/x86/kernel/signal.c:306 exit_to_user_mode_loop kernel/entry/common.c:168 [inline] exit_to_user_mode_prepare+0x15f/0x250 kernel/entry/common.c:203 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline] syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:296 do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f6c19e3c9b9 Code: Unable to access opcode bytes at 0x7f6c19e3c98f. RSP: 002b:00007fffd4ba2ce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: 0000000000000116 RBX: 0000000000000003 RCX: 00007f6c19e3c9b9 RDX: 0000000000000318 RSI: 00000000200bd000 RDI: 0000000000000006 RBP: 0000000000000003 R08: 000000000000000d R09: 000000000000000d R10: 0000000000000000 R11: 0000000000000246 R12: 000055555566a2c0 R13: 0000000000000011 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 5128: kasan_save_stack+0x22/0x40 mm/kasan/common.c:45 kasan_set_track+0x25/0x30 mm/kasan/common.c:52 ____kasan_kmalloc mm/kasan/common.c:371 [inline] ____kasan_kmalloc mm/kasan/common.c:330 [inline] __kasan_kmalloc+0xa3/0xb0 mm/kasan/common.c:380 kasan_kmalloc include/linux/kasan.h:211 [inline] __do_kmalloc_node mm/slab_common.c:968 [inline] __kmalloc+0x5a/0xd0 mm/slab_common.c:981 kmalloc include/linux/slab.h:584 [inline] sk_prot_alloc+0x140/0x290 net/core/sock.c:2038 sk_alloc+0x3a/0x7a0 net/core/sock.c:2091 nr_create+0xb6/0x5f0 net/netrom/af_netrom.c:433 __sock_create+0x359/0x790 net/socket.c:1515 sock_create net/socket.c:1566 [inline] __sys_socket_create net/socket.c:1603 [inline] __sys_socket_create net/socket.c:1588 [inline] __sys_socket+0x133/0x250 net/socket.c:1636 __do_sys_socket net/socket.c:1649 [inline] __se_sys_socket net/socket.c:1647 [inline] __x64_sys_socket+0x73/0xb0 net/socket.c:1647 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Freed by task 5128: kasan_save_stack+0x22/0x40 mm/kasan/common.c:45 kasan_set_track+0x25/0x30 mm/kasan/common.c:52 kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:518 ____kasan_slab_free mm/kasan/common.c:236 [inline] ____kasan_slab_free+0x13b/0x1a0 mm/kasan/common.c:200 kasan_slab_free include/linux/kasan.h:177 [inline] __cache_free mm/slab.c:3394 [inline] __do_kmem_cache_free mm/slab.c:3580 [inline] __kmem_cache_free+0xcd/0x3b0 mm/slab.c:3587 sk_prot_free net/core/sock.c:2074 [inline] __sk_destruct+0x5df/0x750 net/core/sock.c:2166 sk_destruct net/core/sock.c:2181 [inline] __sk_free+0x175/0x460 net/core/sock.c:2192 sk_free+0x7c/0xa0 net/core/sock.c:2203 sock_put include/net/sock.h:1991 [inline] nr_release+0x39e/0x460 net/netrom/af_netrom.c:554 __sock_release+0xcd/0x280 net/socket.c:650 sock_close+0x1c/0x20 net/socket.c:1365 __fput+0x27c/0xa90 fs/file_table.c:320 task_work_run+0x16f/0x270 kernel/task_work.c:179 exit_task_work include/linux/task_work.h:38 [inline] do_exit+0xaa8/0x2950 kernel/exit.c:867 do_group_exit+0xd4/0x2a0 kernel/exit.c:1012 get_signal+0x21c3/0x2450 kernel/signal.c:2859 arch_do_signal_or_restart+0x79/0x5c0 arch/x86/kernel/signal.c:306 exit_to_user_mode_loop kernel/entry/common.c:168 [inline] exit_to_user_mode_prepare+0x15f/0x250 kernel/entry/common.c:203 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline] syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:296 do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x63/0xcd ``` To fix this problem, nr_listen() returns -EINVAL for sockets that successfully nr_connect(). Reported-by: syzbot+caa188bdfc1eeafeb418@syzkaller.appspotmail.com Signed-off-by: Hyunwoo Kim --- net/netrom/af_netrom.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/netrom/af_netrom.c b/net/netrom/af_netrom.c index 6f7f4392cffb..dcfa606684d7 100644 --- a/net/netrom/af_netrom.c +++ b/net/netrom/af_netrom.c @@ -400,6 +400,11 @@ static int nr_listen(struct socket *sock, int backlog) struct sock *sk = sock->sk; lock_sock(sk); + if (sock->state == SS_CONNECTED) { + release_sock(sk); + return -EINVAL; + } + if (sk->sk_state != TCP_LISTEN) { memset(&nr_sk(sk)->user_addr, 0, AX25_ADDR_LEN); sk->sk_max_ack_backlog = backlog;