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 6736DC6FD18 for ; Tue, 18 Apr 2023 18:09:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229564AbjDRSJL (ORCPT ); Tue, 18 Apr 2023 14:09:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43702 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232450AbjDRSJJ (ORCPT ); Tue, 18 Apr 2023 14:09:09 -0400 Received: from smtp-fw-6001.amazon.com (smtp-fw-6001.amazon.com [52.95.48.154]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 79B092718 for ; Tue, 18 Apr 2023 11:09:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1681841348; x=1713377348; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=t7i6P6zTZruAnp5QT/UErqvdAhyp/PGSiVziru6kM0o=; b=KhHMpzohem2NsfGwPBVqj7lIw9UtgIA550pQ0OZacyEZ+d+5U9jEN7Ye VKX2IMVRZ5dEYCAjH+Ki3422m7o34+u/ouzUH3CkLSyKVVbFjZtPInFha a8xGvm8iYQVT8z7BUeqv0u3TQDs0u9K7+k1W87Rv9CWcAS6zn4DOY5Ktc 0=; X-IronPort-AV: E=Sophos;i="5.99,207,1677542400"; d="scan'208";a="321860061" Received: from iad12-co-svc-p1-lb1-vlan2.amazon.com (HELO email-inbound-relay-iad-1a-m6i4x-9fe6ad2f.us-east-1.amazon.com) ([10.43.8.2]) by smtp-border-fw-6001.iad6.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Apr 2023 18:09:03 +0000 Received: from EX19MTAUWB002.ant.amazon.com (iad12-ws-svc-p26-lb9-vlan3.iad.amazon.com [10.40.163.38]) by email-inbound-relay-iad-1a-m6i4x-9fe6ad2f.us-east-1.amazon.com (Postfix) with ESMTPS id 710D580CE6; Tue, 18 Apr 2023 18:09:01 +0000 (UTC) Received: from EX19D004ANA001.ant.amazon.com (10.37.240.138) by EX19MTAUWB002.ant.amazon.com (10.250.64.231) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.25; Tue, 18 Apr 2023 18:08:51 +0000 Received: from 88665a182662.ant.amazon.com.com (10.106.101.27) 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 15.2.1118.26; Tue, 18 Apr 2023 18:08:48 +0000 From: Kuniyuki Iwashima To: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni CC: Willem de Bruijn , Kuniyuki Iwashima , Kuniyuki Iwashima , , syzbot Subject: [PATCH v2 net] tcp/udp: Fix memleaks of sk and zerocopy skbs with TX timestamp. Date: Tue, 18 Apr 2023 11:08:32 -0700 Message-ID: <20230418180832.81430-1-kuniyu@amazon.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.106.101.27] X-ClientProxiedBy: EX19D041UWA003.ant.amazon.com (10.13.139.105) To EX19D004ANA001.ant.amazon.com (10.37.240.138) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org syzkaller reported [0] memory leaks of an UDP socket and ZEROCOPY skbs. We can reproduce the problem with these sequences: sk = socket(AF_INET, SOCK_DGRAM, 0) sk.setsockopt(SOL_SOCKET, SO_TIMESTAMPING, SOF_TIMESTAMPING_TX_SOFTWARE) sk.setsockopt(SOL_SOCKET, SO_ZEROCOPY, 1) sk.sendto(b'', MSG_ZEROCOPY, ('127.0.0.1', 53)) sk.close() sendmsg() calls msg_zerocopy_alloc(), which allocates a skb, sets skb->cb->ubuf.refcnt to 1, and calls sock_hold(). Here, struct ubuf_info_msgzc indirectly holds a refcnt of the socket. When the skb is sent, __skb_tstamp_tx() clones it and puts the clone into the socket's error queue with the TX timestamp. When the original skb is received locally, skb_copy_ubufs() calls skb_unclone(), and pskb_expand_head() increments skb->cb->ubuf.refcnt. This additional count is decremented while freeing the skb, but struct ubuf_info_msgzc still has a refcnt, so __msg_zerocopy_callback() is not called. The last refcnt is not released unless we retrieve the TX timestamped skb by recvmsg(). When we close() the socket holding such skb, we never call sock_put() and leak the count, skb, and sk. To avoid this problem, we must (i) call skb_queue_purge() after flagging SOCK_DEAD during close() and (ii) make sure that TX tstamp skb is not queued when SOCK_DEAD is flagged. UDP lacks (i) and (ii), and TCP lacks (ii). Without (ii), a skb queued in a qdisc or device could be put into the error queue after skb_queue_purge(). sendmsg() /* return immediately, but packets * are queued in a qdisc or device */ close() skb_queue_purge() __skb_tstamp_tx() __skb_complete_tx_timestamp() sock_queue_err_skb() skb_queue_tail() Also, we need to check SOCK_DEAD under sk->sk_error_queue.lock in sock_queue_err_skb() to avoid this race. if (!sock_flag(sk, SOCK_DEAD)) sock_set_flag(sk, SOCK_DEAD) skb_queue_purge() skb_queue_tail() [0]: BUG: memory leak unreferenced object 0xffff88800c6d2d00 (size 1152): comm "syz-executor392", pid 264, jiffies 4294785440 (age 13.044s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 cd af e8 81 00 00 00 00 ................ 02 00 07 40 00 00 00 00 00 00 00 00 00 00 00 00 ...@............ backtrace: [<0000000055636812>] sk_prot_alloc+0x64/0x2a0 net/core/sock.c:2024 [<0000000054d77b7a>] sk_alloc+0x3b/0x800 net/core/sock.c:2083 [<0000000066f3c7e0>] inet_create net/ipv4/af_inet.c:319 [inline] [<0000000066f3c7e0>] inet_create+0x31e/0xe40 net/ipv4/af_inet.c:245 [<000000009b83af97>] __sock_create+0x2ab/0x550 net/socket.c:1515 [<00000000b9b11231>] sock_create net/socket.c:1566 [inline] [<00000000b9b11231>] __sys_socket_create net/socket.c:1603 [inline] [<00000000b9b11231>] __sys_socket_create net/socket.c:1588 [inline] [<00000000b9b11231>] __sys_socket+0x138/0x250 net/socket.c:1636 [<000000004fb45142>] __do_sys_socket net/socket.c:1649 [inline] [<000000004fb45142>] __se_sys_socket net/socket.c:1647 [inline] [<000000004fb45142>] __x64_sys_socket+0x73/0xb0 net/socket.c:1647 [<0000000066999e0e>] do_syscall_x64 arch/x86/entry/common.c:50 [inline] [<0000000066999e0e>] do_syscall_64+0x38/0x90 arch/x86/entry/common.c:80 [<0000000017f238c1>] entry_SYSCALL_64_after_hwframe+0x63/0xcd BUG: memory leak unreferenced object 0xffff888017633a00 (size 240): comm "syz-executor392", pid 264, jiffies 4294785440 (age 13.044s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 2d 6d 0c 80 88 ff ff .........-m..... backtrace: [<000000002b1c4368>] __alloc_skb+0x229/0x320 net/core/skbuff.c:497 [<00000000143579a6>] alloc_skb include/linux/skbuff.h:1265 [inline] [<00000000143579a6>] sock_omalloc+0xaa/0x190 net/core/sock.c:2596 [<00000000be626478>] msg_zerocopy_alloc net/core/skbuff.c:1294 [inline] [<00000000be626478>] msg_zerocopy_realloc+0x1ce/0x7f0 net/core/skbuff.c:1370 [<00000000cbfc9870>] __ip_append_data+0x2adf/0x3b30 net/ipv4/ip_output.c:1037 [<0000000089869146>] ip_make_skb+0x26c/0x2e0 net/ipv4/ip_output.c:1652 [<00000000098015c2>] udp_sendmsg+0x1bac/0x2390 net/ipv4/udp.c:1253 [<0000000045e0e95e>] inet_sendmsg+0x10a/0x150 net/ipv4/af_inet.c:819 [<000000008d31bfde>] sock_sendmsg_nosec net/socket.c:714 [inline] [<000000008d31bfde>] sock_sendmsg+0x141/0x190 net/socket.c:734 [<0000000021e21aa4>] __sys_sendto+0x243/0x360 net/socket.c:2117 [<00000000ac0af00c>] __do_sys_sendto net/socket.c:2129 [inline] [<00000000ac0af00c>] __se_sys_sendto net/socket.c:2125 [inline] [<00000000ac0af00c>] __x64_sys_sendto+0xe1/0x1c0 net/socket.c:2125 [<0000000066999e0e>] do_syscall_x64 arch/x86/entry/common.c:50 [inline] [<0000000066999e0e>] do_syscall_64+0x38/0x90 arch/x86/entry/common.c:80 [<0000000017f238c1>] entry_SYSCALL_64_after_hwframe+0x63/0xcd Fixes: f214f915e7db ("tcp: enable MSG_ZEROCOPY") Fixes: b5947e5d1e71 ("udp: msg_zerocopy") Reported-by: syzbot Signed-off-by: Kuniyuki Iwashima --- v2: * Move skb_queue_purge() after setting SOCK_DEAD in udp_destroy_sock() * Check SOCK_DEAD in sock_queue_err_skb() with sk_error_queue.lock * Add Fixes tag for TCP v1: https://lore.kernel.org/netdev/20230417171155.22916-1-kuniyu@amazon.com/ --- net/core/skbuff.c | 15 ++++++++++++--- net/ipv4/udp.c | 5 +++++ 2 files changed, 17 insertions(+), 3 deletions(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 4c0879798eb8..287b834df9c8 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -4979,6 +4979,8 @@ static void skb_set_err_queue(struct sk_buff *skb) */ int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb) { + unsigned long flags; + if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >= (unsigned int)READ_ONCE(sk->sk_rcvbuf)) return -ENOMEM; @@ -4992,9 +4994,16 @@ int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb) /* before exiting rcu section, make sure dst is refcounted */ skb_dst_force(skb); - skb_queue_tail(&sk->sk_error_queue, skb); - if (!sock_flag(sk, SOCK_DEAD)) - sk_error_report(sk); + spin_lock_irqsave(&sk->sk_error_queue.lock, flags); + if (sock_flag(sk, SOCK_DEAD)) { + spin_unlock_irqrestore(&sk->sk_error_queue.lock, flags); + return -EINVAL; + } + __skb_queue_tail(&sk->sk_error_queue, skb); + spin_unlock_irqrestore(&sk->sk_error_queue.lock, flags); + + sk_error_report(sk); + return 0; } EXPORT_SYMBOL(sock_queue_err_skb); diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index c605d171eb2d..7060a5cda711 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -2674,6 +2674,11 @@ void udp_destroy_sock(struct sock *sk) if (up->encap_enabled) static_branch_dec(&udp_encap_needed_key); } + + /* A zerocopy skb has a refcnt of sk and may be + * put into sk_error_queue with TX timestamp + */ + skb_queue_purge(&sk->sk_error_queue); } /* -- 2.30.2