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 CC40DC19F2A for ; Sun, 7 Aug 2022 09:00:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233134AbiHGJAv (ORCPT ); Sun, 7 Aug 2022 05:00:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52868 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231971AbiHGJAf (ORCPT ); Sun, 7 Aug 2022 05:00:35 -0400 Received: from mail-pf1-x431.google.com (mail-pf1-x431.google.com [IPv6:2607:f8b0:4864:20::431]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AB9116171; Sun, 7 Aug 2022 02:00:34 -0700 (PDT) Received: by mail-pf1-x431.google.com with SMTP id 130so5743753pfv.13; Sun, 07 Aug 2022 02:00:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=Qni0rYee/HlsJdTHd9Y+kIdaIsYANJdmYzeddwDHiNw=; b=VfQz50S8RfV298NAMsS+nYuT0HjQPFM2Hq5XLD8SWew8UXwnd6cgUko+0zb9zSShrB ITkHN23L0yQV2jJwq255bo7XArVhXDDb+vbiRC7Nfmb06N0bqqxLb+BDP9rFQQS8hhSs 5N8WuAlFEQQ1C3hui56D6ow/3HBiBAl8fxc9vuRP7EUZ6zzANdUOJT7pJvne5sr2k5lX Spnzp5MxB5ppyCqkX7n7ZPknVn1ySuUj/FUoZXEvNuBr0MVCSuw+469fMAUOXZs2O6rt P9J57PXexAPFoJLe0aU+7O8aYqBm5o4ljLINGuaNC4pioN1MqRUNePNKPtRaOjDuccOO gddg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=Qni0rYee/HlsJdTHd9Y+kIdaIsYANJdmYzeddwDHiNw=; b=0Mld0R6cyJS1xx37/1q8GukdE0Q1q3q0L89JwDT8h2ciFyO6TWgDBqKdthAMvp2ILA bhF1WOiILYLOVQutztpyO3VqDH9H2Eu4/GG9UF4wBMcVwzNmJBNmuoidRsTGaamJi+DN Qt1gobLuay2hw3ZP0HnFxePuxyxemscs9NX2b+4cumu8IscrG16/4Lpa+61ek1jPITaY 0xWQ3u8jyehQFhxCodEvINSklS8ah4zEGjeXi03sizJh1OKYuVaSO5t1cPq/0eqCoPn8 7QtmA/9mQLLNyH+8hh+MLn3sJvns3U5rZsiFdFKOxpIWkibaToSup7uAdJuetdKkWjoW kGCw== X-Gm-Message-State: ACgBeo1BjnmpDMEVPHa2LciMgfj+/U9W7mffbgh5fjRKzTGlavG3Q8MM b8df90XjRmWSIxrS5UjNOg/+ZfcoCkgb X-Google-Smtp-Source: AA6agR6o8zVY6NM0xbsMJ9hAvP/vBEi4bM5/pJPGmSg0qc1NRRl29LxZw0QoIeA7oylI+odM8JYWOA== X-Received: by 2002:aa7:8e91:0:b0:52d:8ebf:29a4 with SMTP id a17-20020aa78e91000000b0052d8ebf29a4mr14222576pfr.1.1659862833974; Sun, 07 Aug 2022 02:00:33 -0700 (PDT) Received: from bytedance.attlocal.net ([139.177.225.235]) by smtp.gmail.com with ESMTPSA id d14-20020a170902654e00b0016ed715d244sm6183912pln.300.2022.08.07.02.00.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 07 Aug 2022 02:00:33 -0700 (PDT) From: Peilin Ye To: Stefano Garzarella , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: Peilin Ye , George Zhang , Dmitry Torokhov , Andy King , virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Peilin Ye Subject: [PATCH net v2 1/2] vsock: Fix memory leak in vsock_connect() Date: Sun, 7 Aug 2022 02:00:11 -0700 Message-Id: X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220804020925.32167-1-yepeilin.cs@gmail.com> References: <20220804020925.32167-1-yepeilin.cs@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Peilin Ye An O_NONBLOCK vsock_connect() request may try to reschedule @connect_work. Imagine the following sequence of vsock_connect() requests: 1. The 1st, non-blocking request schedules @connect_work, which will expire after 200 jiffies. Socket state is now SS_CONNECTING; 2. Later, the 2nd, blocking request gets interrupted by a signal after a few jiffies while waiting for the connection to be established. Socket state is back to SS_UNCONNECTED, but @connect_work is still pending, and will expire after 100 jiffies. 3. Now, the 3rd, non-blocking request tries to schedule @connect_work again. Since @connect_work is already scheduled, schedule_delayed_work() silently returns. sock_hold() is called twice, but sock_put() will only be called once in vsock_connect_timeout(), causing a memory leak reported by syzbot: BUG: memory leak unreferenced object 0xffff88810ea56a40 (size 1232): comm "syz-executor756", pid 3604, jiffies 4294947681 (age 12.350s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 28 00 07 40 00 00 00 00 00 00 00 00 00 00 00 00 (..@............ backtrace: [] sk_prot_alloc+0x3e/0x1b0 net/core/sock.c:1930 [] sk_alloc+0x32/0x2e0 net/core/sock.c:1989 [] __vsock_create.constprop.0+0x38/0x320 net/vmw_vsock/af_vsock.c:734 [] vsock_create+0xc1/0x2d0 net/vmw_vsock/af_vsock.c:2203 [] __sock_create+0x1ab/0x2b0 net/socket.c:1468 [] sock_create net/socket.c:1519 [inline] [] __sys_socket+0x6f/0x140 net/socket.c:1561 [] __do_sys_socket net/socket.c:1570 [inline] [] __se_sys_socket net/socket.c:1568 [inline] [] __x64_sys_socket+0x1a/0x20 net/socket.c:1568 [] do_syscall_x64 arch/x86/entry/common.c:50 [inline] [] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80 [] entry_SYSCALL_64_after_hwframe+0x44/0xae <...> Use mod_delayed_work() instead: if @connect_work is already scheduled, reschedule it, and undo sock_hold() to keep the reference count balanced. Reported-and-tested-by: syzbot+b03f55bf128f9a38f064@syzkaller.appspotmail.com Fixes: d021c344051a ("VSOCK: Introduce VM Sockets") Co-developed-by: Stefano Garzarella Signed-off-by: Stefano Garzarella Signed-off-by: Peilin Ye --- change since v1: - merged with Stefano's patch [1] [1] https://gitlab.com/sgarzarella/linux/-/commit/2d0f0b9cbbb30d58fdcbca7c1a857fd8f3110d61 Hi Stefano, About the Fixes: tag, [2] introduced @connect_work, but all it did was breaking @dwork into two and moving some INIT_DELAYED_WORK()'s, so I don't think [2] introduced this memory leak? Since [2] has already been backported to 4.9 and 4.14, I think we can Fixes: commit d021c344051a ("VSOCK: Introduce VM Sockets"), too, to make backporting easier? [2] commit 455f05ecd2b2 ("vsock: split dwork to avoid reinitializations") Thanks, Peilin Ye net/vmw_vsock/af_vsock.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c index f04abf662ec6..fe14f6cbca22 100644 --- a/net/vmw_vsock/af_vsock.c +++ b/net/vmw_vsock/af_vsock.c @@ -1391,7 +1391,13 @@ static int vsock_connect(struct socket *sock, struct sockaddr *addr, * timeout fires. */ sock_hold(sk); - schedule_delayed_work(&vsk->connect_work, timeout); + + /* If the timeout function is already scheduled, + * reschedule it, then ungrab the socket refcount to + * keep it balanced. + */ + if (mod_delayed_work(system_wq, &vsk->connect_work, timeout)) + sock_put(sk); /* Skip ahead to preserve error code set above. */ goto out_wait; -- 2.20.1