From mboxrd@z Thu Jan 1 00:00:00 1970 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 60448C77B76 for ; Tue, 18 Apr 2023 12:50:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232133AbjDRMuO (ORCPT ); Tue, 18 Apr 2023 08:50:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42012 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232132AbjDRMuL (ORCPT ); Tue, 18 Apr 2023 08:50:11 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 14CC716DE5 for ; Tue, 18 Apr 2023 05:50:10 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id A3E31633F4 for ; Tue, 18 Apr 2023 12:50:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BC2E7C4339B; Tue, 18 Apr 2023 12:50:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1681822209; bh=izZKBrFPUX9A1vIZgGaZ0mPYuSsmWRCnnERQMNubdzA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=e5zf9GyWEskEm/E3sqbwNJcivfmcV1+QKqDQTyhhA3EEOaNaX4+t0x4cV9lAugNeu avC/QcGnvoWMAdHgJlMk8wto/rcykzq/59vxv2u/hdXulN69phBNh+QSbckN+k44P1 eGJklUeh0oIFusn909kXu65o6+ykZbEaf2W5uomU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+7e1e1bdb852961150198@syzkaller.appspotmail.com, Kuniyuki Iwashima , Tony Lu , "David S. Miller" , Sasha Levin Subject: [PATCH 6.2 063/139] smc: Fix use-after-free in tcp_write_timer_handler(). Date: Tue, 18 Apr 2023 14:22:08 +0200 Message-Id: <20230418120316.163050105@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230418120313.725598495@linuxfoundation.org> References: <20230418120313.725598495@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Kuniyuki Iwashima [ Upstream commit 9744d2bf19762703704ecba885b7ac282c02eacf ] With Eric's ref tracker, syzbot finally found a repro for use-after-free in tcp_write_timer_handler() by kernel TCP sockets. [0] If SMC creates a kernel socket in __smc_create(), the kernel socket is supposed to be freed in smc_clcsock_release() by calling sock_release() when we close() the parent SMC socket. However, at the end of smc_clcsock_release(), the kernel socket's sk_state might not be TCP_CLOSE. This means that we have not called inet_csk_destroy_sock() in __tcp_close() and have not stopped the TCP timers. The kernel socket's TCP timers can be fired later, so we need to hold a refcnt for net as we do for MPTCP subflows in mptcp_subflow_create_socket(). [0]: leaked reference. sk_alloc (./include/net/net_namespace.h:335 net/core/sock.c:2108) inet_create (net/ipv4/af_inet.c:319 net/ipv4/af_inet.c:244) __sock_create (net/socket.c:1546) smc_create (net/smc/af_smc.c:3269 net/smc/af_smc.c:3284) __sock_create (net/socket.c:1546) __sys_socket (net/socket.c:1634 net/socket.c:1618 net/socket.c:1661) __x64_sys_socket (net/socket.c:1672) do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120) ================================================================== BUG: KASAN: slab-use-after-free in tcp_write_timer_handler (net/ipv4/tcp_timer.c:378 net/ipv4/tcp_timer.c:624 net/ipv4/tcp_timer.c:594) Read of size 1 at addr ffff888052b65e0d by task syzrepro/18091 CPU: 0 PID: 18091 Comm: syzrepro Tainted: G W 6.3.0-rc4-01174-gb5d54eb5899a #7 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-1.amzn2022.0.1 04/01/2014 Call Trace: dump_stack_lvl (lib/dump_stack.c:107) print_report (mm/kasan/report.c:320 mm/kasan/report.c:430) kasan_report (mm/kasan/report.c:538) tcp_write_timer_handler (net/ipv4/tcp_timer.c:378 net/ipv4/tcp_timer.c:624 net/ipv4/tcp_timer.c:594) tcp_write_timer (./include/linux/spinlock.h:390 net/ipv4/tcp_timer.c:643) 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:2022) run_timer_softirq (kernel/time/timer.c:2037) __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:572) __irq_exit_rcu (kernel/softirq.c:445 kernel/softirq.c:650) irq_exit_rcu (kernel/softirq.c:664) sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1107 (discriminator 14)) Fixes: ac7138746e14 ("smc: establish new socket family") Reported-by: syzbot+7e1e1bdb852961150198@syzkaller.appspotmail.com Link: https://lore.kernel.org/netdev/000000000000a3f51805f8bcc43a@google.com/ Signed-off-by: Kuniyuki Iwashima Reviewed-by: Tony Lu Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/smc/af_smc.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c index e8018b0fb7676..bdeaee727538d 100644 --- a/net/smc/af_smc.c +++ b/net/smc/af_smc.c @@ -3257,6 +3257,17 @@ static int __smc_create(struct net *net, struct socket *sock, int protocol, sk_common_release(sk); goto out; } + + /* smc_clcsock_release() does not wait smc->clcsock->sk's + * destruction; its sk_state might not be TCP_CLOSE after + * smc->sk is close()d, and TCP timers can be fired later, + * which need net ref. + */ + sk = smc->clcsock->sk; + __netns_tracker_free(net, &sk->ns_tracker, false); + sk->sk_net_refcnt = 1; + get_net_track(net, &sk->ns_tracker, GFP_KERNEL); + sock_inuse_add(net, 1); } else { smc->clcsock = clcsock; } -- 2.39.2