From patchwork Fri Feb 23 17:24:48 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kuniyuki Iwashima X-Patchwork-Id: 13569628 Received: from smtp-fw-52005.amazon.com (smtp-fw-52005.amazon.com [52.119.213.156]) (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 6F14720DF8; Fri, 23 Feb 2024 17:26:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=52.119.213.156 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708709167; cv=none; b=oaL1lKv+cHdLtCZr6cYSE9LkVWVSV+6pncK3cRkMlkcIcqOwsKWOgIo/hlNJ2FyVguFMAF4tQ0tZ7yyOELIJ8koxSSkDQaCh1hQv24Rcg8jSeKwECSxpyL8d7YhhARHETsvPFERbo7EoWEIb/AQmojkzdW4vVE4O/3L8tuQg2is= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708709167; c=relaxed/simple; bh=7fed7ePXHCkzI4CFJ5+VUwNztvIdR0Yb/YSif4y8Ddw=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=tO99U7Z1wBgcRnl2ijCm1unbgqSpE5gUeRx07A34NLUT49dyv/dobowiR+GVmNLMTLHcaq5FTjDzTdyqBGIKsNvhbckjvk34njFOl6CqaKHXzRCOv7WY3bcAEapXtM1a3nO9bIay9K4gjATw5iVbu6xO2s1P/pT1afQzlN7tYb0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com; spf=pass smtp.mailfrom=amazon.co.jp; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b=BABycqrm; arc=none smtp.client-ip=52.119.213.156 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amazon.co.jp Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="BABycqrm" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1708709165; x=1740245165; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=Hu0uLmoy54JYHokYsSpP8/4WedLN2zGC+4CnLikdlrY=; b=BABycqrmlmM8jFQjKPvaKEeK1vg6gvetF6G5atdTmcssOzMHEQjHoAgF VDYsRkKu8A4PLIIl1HXpZ/kJBbMsMndB1VhvZ7WrH/k7FRt5GBJj8MQyE iB6cF3fDzWVB6PfdojuzOc1pL+mcPyV6lesiGwAJzvrZS8HVXKzKw/6e2 k=; X-IronPort-AV: E=Sophos;i="6.06,180,1705363200"; d="scan'208";a="636375394" Received: from iad12-co-svc-p1-lb1-vlan3.amazon.com (HELO smtpout.prod.us-west-2.prod.farcaster.email.amazon.dev) ([10.43.8.6]) by smtp-border-fw-52005.iad7.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Feb 2024 17:26:02 +0000 Received: from EX19MTAUWC001.ant.amazon.com [10.0.7.35:29814] by smtpin.naws.us-west-2.prod.farcaster.email.amazon.dev [10.0.23.221:2525] with esmtp (Farcaster) id 77113ec9-ab22-4ea5-8b69-a3a0fea2ef69; Fri, 23 Feb 2024 17:26:00 +0000 (UTC) X-Farcaster-Flow-ID: 77113ec9-ab22-4ea5-8b69-a3a0fea2ef69 Received: from EX19D004ANA001.ant.amazon.com (10.37.240.138) by EX19MTAUWC001.ant.amazon.com (10.250.64.174) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.40; Fri, 23 Feb 2024 17:25:59 +0000 Received: from 88665a182662.ant.amazon.com (10.106.100.9) 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 15.2.1118.40; Fri, 23 Feb 2024 17:25:56 +0000 From: Kuniyuki Iwashima To: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Allison Henderson CC: Sowmini Varadhan , Kuniyuki Iwashima , Kuniyuki Iwashima , , , , syzkaller Subject: [PATCH v1 net 2/2] rds: tcp: Fix use-after-free of net in reqsk_timer_handler(). Date: Fri, 23 Feb 2024 09:24:48 -0800 Message-ID: <20240223172448.94084-3-kuniyu@amazon.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20240223172448.94084-1-kuniyu@amazon.com> References: <20240223172448.94084-1-kuniyu@amazon.com> Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: EX19D039UWA002.ant.amazon.com (10.13.139.32) To EX19D004ANA001.ant.amazon.com (10.37.240.138) syzkaller reported a warning of netns tracker [0] followed by KASAN splat [1] and another ref tracker warning [1]. syzkaller could not find a repro, but in the log, the only suspicious sequence was as follows: 18:26:22 executing program 1: r0 = socket$inet6_mptcp(0xa, 0x1, 0x106) ... connect$inet6(r0, &(0x7f0000000080)={0xa, 0x4001, 0x0, @loopback}, 0x1c) (async) The notable thing here is 0x4001 in connect(), which is RDS_TCP_PORT. So, the scenario would be: 1. unshare(CLONE_NEWNET) creates a per netns tcp listener in rds_tcp_listen_init(). 2. syz-executor connect()s to it and creates a reqsk. 3. syz-executor exit()s immediately. 4. netns is dismantled. [0] 5. reqsk timer is fired, and UAF happens while freeing reqsk. [1] 6. listener is freed after RCU grace period. [2] Basically, reqsk assumes that the listener guarantees netns safety until all reqsk timers are expired by holding the listener's refcount. However, this was not the case for kernel sockets. Commit 740ea3c4a0b2 ("tcp: Clean up kernel listener's reqsk in inet_twsk_purge()") fixed this issue only for per-netns ehash, but the issue still exists for the global ehash. We can apply the same fix, but this issue is specific to RDS. Instead of iterating potentially large ehash and purging reqsk during netns dismantle, let's hold netns refcount for the kernel TCP listener. [0]: ref_tracker: net notrefcnt@0000000065449cc3 has 1/1 users at sk_alloc (./include/net/net_namespace.h:337 net/core/sock.c:2146) inet6_create (net/ipv6/af_inet6.c:192 net/ipv6/af_inet6.c:119) __sock_create (net/socket.c:1572) rds_tcp_listen_init (net/rds/tcp_listen.c:279) rds_tcp_init_net (net/rds/tcp.c:577) ops_init (net/core/net_namespace.c:137) setup_net (net/core/net_namespace.c:340) copy_net_ns (net/core/net_namespace.c:497) create_new_namespaces (kernel/nsproxy.c:110) unshare_nsproxy_namespaces (kernel/nsproxy.c:228 (discriminator 4)) ksys_unshare (kernel/fork.c:3429) __x64_sys_unshare (kernel/fork.c:3496) do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:129) ... WARNING: CPU: 0 PID: 27 at lib/ref_tracker.c:179 ref_tracker_dir_exit (lib/ref_tracker.c:179) [1]: BUG: KASAN: slab-use-after-free in inet_csk_reqsk_queue_drop (./include/net/inet_hashtables.h:180 net/ipv4/inet_connection_sock.c:952 net/ipv4/inet_connection_sock.c:966) Read of size 8 at addr ffff88801b370400 by task swapper/0/0 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 Call Trace: dump_stack_lvl (lib/dump_stack.c:107 (discriminator 1)) print_report (mm/kasan/report.c:378 mm/kasan/report.c:488) kasan_report (mm/kasan/report.c:603) inet_csk_reqsk_queue_drop (./include/net/inet_hashtables.h:180 net/ipv4/inet_connection_sock.c:952 net/ipv4/inet_connection_sock.c:966) reqsk_timer_handler (net/ipv4/inet_connection_sock.c:979 net/ipv4/inet_connection_sock.c:1092) call_timer_fn (./arch/x86/include/asm/jump_label.h:27 ./include/linux/jump_label.h:207 ./include/trace/events/timer.h:127 kernel/time/timer.c:1701) __run_timers.part.0 (kernel/time/timer.c:1752 kernel/time/timer.c:2038) run_timer_softirq (kernel/time/timer.c:2053) __do_softirq (./arch/x86/include/asm/jump_label.h:27 ./include/linux/jump_label.h:207 ./include/trace/events/irq.h:142 kernel/softirq.c:554) irq_exit_rcu (kernel/softirq.c:427 kernel/softirq.c:632 kernel/softirq.c:644) sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1076 (discriminator 14)) Allocated by task 258 on cpu 0 at 83.612050s: kasan_save_stack (mm/kasan/common.c:48) kasan_save_track (mm/kasan/common.c:68) __kasan_slab_alloc (mm/kasan/common.c:343) kmem_cache_alloc (mm/slub.c:3813 mm/slub.c:3860 mm/slub.c:3867) copy_net_ns (./include/linux/slab.h:701 net/core/net_namespace.c:421 net/core/net_namespace.c:480) create_new_namespaces (kernel/nsproxy.c:110) unshare_nsproxy_namespaces (kernel/nsproxy.c:228 (discriminator 4)) ksys_unshare (kernel/fork.c:3429) __x64_sys_unshare (kernel/fork.c:3496) do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:129) Freed by task 27 on cpu 0 at 329.158864s: kasan_save_stack (mm/kasan/common.c:48) kasan_save_track (mm/kasan/common.c:68) kasan_save_free_info (mm/kasan/generic.c:643) __kasan_slab_free (mm/kasan/common.c:265) kmem_cache_free (mm/slub.c:4299 mm/slub.c:4363) cleanup_net (net/core/net_namespace.c:456 net/core/net_namespace.c:446 net/core/net_namespace.c:639) process_one_work (kernel/workqueue.c:2638) worker_thread (kernel/workqueue.c:2700 kernel/workqueue.c:2787) kthread (kernel/kthread.c:388) ret_from_fork (arch/x86/kernel/process.c:153) ret_from_fork_asm (arch/x86/entry/entry_64.S:250) The buggy address belongs to the object at ffff88801b370000 which belongs to the cache net_namespace of size 4352 The buggy address is located 1024 bytes inside of freed 4352-byte region [ffff88801b370000, ffff88801b371100) [2]: WARNING: CPU: 0 PID: 95 at lib/ref_tracker.c:228 ref_tracker_free (lib/ref_tracker.c:228 (discriminator 1)) Modules linked in: Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 RIP: 0010:ref_tracker_free (lib/ref_tracker.c:228 (discriminator 1)) ... Call Trace: __sk_destruct (./include/net/net_namespace.h:353 net/core/sock.c:2204) rcu_core (./arch/x86/include/asm/preempt.h:26 kernel/rcu/tree.c:2165 kernel/rcu/tree.c:2433) __do_softirq (./arch/x86/include/asm/jump_label.h:27 ./include/linux/jump_label.h:207 ./include/trace/events/irq.h:142 kernel/softirq.c:554) irq_exit_rcu (kernel/softirq.c:427 kernel/softirq.c:632 kernel/softirq.c:644) sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1076 (discriminator 14)) Reported-by: syzkaller Fixes: 467fa15356ac ("RDS-TCP: Support multiple RDS-TCP listen endpoints, one per netns.") Signed-off-by: Kuniyuki Iwashima --- net/rds/tcp_listen.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/rds/tcp_listen.c b/net/rds/tcp_listen.c index 05008ce5c421..4f7863932df7 100644 --- a/net/rds/tcp_listen.c +++ b/net/rds/tcp_listen.c @@ -282,6 +282,11 @@ struct socket *rds_tcp_listen_init(struct net *net, bool isv6) goto out; } + __netns_tracker_free(net, &sock->sk->ns_tracker, false); + sock->sk->sk_net_refcnt = 1; + get_net_track(net, &sock->sk->ns_tracker, GFP_KERNEL); + sock_inuse_add(net, 1); + sock->sk->sk_reuse = SK_CAN_REUSE; tcp_sock_set_nodelay(sock->sk);