From patchwork Fri Aug 5 07:48:34 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hawkins Jiawei X-Patchwork-Id: 12937025 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 1B6F5C25B0C for ; Fri, 5 Aug 2022 07:48:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240175AbiHEHsw (ORCPT ); Fri, 5 Aug 2022 03:48:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48738 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237624AbiHEHsu (ORCPT ); Fri, 5 Aug 2022 03:48:50 -0400 Received: from mail-pl1-x632.google.com (mail-pl1-x632.google.com [IPv6:2607:f8b0:4864:20::632]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2834B1018; Fri, 5 Aug 2022 00:48:47 -0700 (PDT) Received: by mail-pl1-x632.google.com with SMTP id w14so1960084plp.9; Fri, 05 Aug 2022 00:48:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc; bh=7UBWNlO3fLQxQeZLzmYhtN9S9nLT0WpSVtJngbc+X2w=; b=eGEcg3HVdqx+0OUna1SJ8l7FDJ0Wai0IltIGS84nmsXrLOzxepd7XFK6P9qZS4aXJR QVz+CAPB37lfcElohvPaTg1sa8OAOkILxUC6zBVeuPkS2pBUlj1xKAy+A/CeP5mqgga4 qoG2FxfRqAZ6tcLVjAbZHFk/ycc5l53Xh7t23Kd8nCyOTd7GBtF2Tp9HXxMI0EGC+wJo CrFaoWRlhawGqZAS7C+dgU5OSApVOKUaH98G54TBqhuP+mGuU4sLBDinKJ3+poqPzLju Yjz6NEYvKjREhoq6WFqV9vbp3jHvlk0bqWAQa1l/aTP06cMq+LuY4SRDCjHzzESXLyGr wGtw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc; bh=7UBWNlO3fLQxQeZLzmYhtN9S9nLT0WpSVtJngbc+X2w=; b=xdWq2/WzjlZpzx5bd3pR/Em02lVfFwM3W63h0uEXgABW806h+J/tCwdMhfzHAYkM2/ 8BMSt1Lr0iFbbjkfbtVj7TLx8KmAhI3eycR/MvDl5qqrtlqfchKwnxLMDmMCSS2fcbY8 VyO0BUfmWq5bzQ983gOf3uXPLBat/ztQoQ7aBI/HUIxAqOXOE0YU8ptAS3k7dzMi8eFn sb6Q5iTHPrBFz7JIaNSfV1CquAkjGQBFyz8eSMYMgcFd1aLPRwQTUV7PdnhTSFmnWMe3 tXN92/v1mWcFwdsTma1xk6qRdWnIQn4Eyxi62udZpH2mZJEuiJSoVCV8tP0PoLNQnTCo PInA== X-Gm-Message-State: ACgBeo28vNZjePfJ3tGGriMdCEi0ceaVlhyLsNJDIWaj0iJn/1GwFlsn uUhR4gqS5fQ/hoxsJyjvxiI= X-Google-Smtp-Source: AA6agR6v4QLqjaMArP3sGgtyrw+Fmdy7UThiHNXhJHmkKvwTz+wx+iDMM6m/R7il/6yPKy41XuxL7w== X-Received: by 2002:a17:90b:508a:b0:1f3:3a77:4fde with SMTP id rt10-20020a17090b508a00b001f33a774fdemr6262387pjb.130.1659685726683; Fri, 05 Aug 2022 00:48:46 -0700 (PDT) Received: from localhost ([117.136.0.155]) by smtp.gmail.com with ESMTPSA id u13-20020a170902714d00b0016d2f0b67e0sm2158889plm.309.2022.08.05.00.48.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 05 Aug 2022 00:48:46 -0700 (PDT) From: Hawkins Jiawei To: syzbot+5f26f85569bd179c18ce@syzkaller.appspotmail.com, John Fastabend , Jakub Sitnicki , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: paskripkin@gmail.com, skhan@linuxfoundation.org, linux-kernel-mentees@lists.linuxfoundation.org, 18801353760@163.com, Hawkins Jiawei , Wen Gu , netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH net v5 1/2] net: fix refcount bug in sk_psock_get (2) Date: Fri, 5 Aug 2022 15:48:34 +0800 Message-Id: <785e4e5b6f7375c3e7d7cfb169d34852c1380587.1659676823.git.yin31149@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org Syzkaller reports refcount bug as follows: ------------[ cut here ]------------ refcount_t: saturated; leaking memory. WARNING: CPU: 1 PID: 3605 at lib/refcount.c:19 refcount_warn_saturate+0xf4/0x1e0 lib/refcount.c:19 Modules linked in: CPU: 1 PID: 3605 Comm: syz-executor208 Not tainted 5.18.0-syzkaller-03023-g7e062cda7d90 #0 __refcount_add_not_zero include/linux/refcount.h:163 [inline] __refcount_inc_not_zero include/linux/refcount.h:227 [inline] refcount_inc_not_zero include/linux/refcount.h:245 [inline] sk_psock_get+0x3bc/0x410 include/linux/skmsg.h:439 tls_data_ready+0x6d/0x1b0 net/tls/tls_sw.c:2091 tcp_data_ready+0x106/0x520 net/ipv4/tcp_input.c:4983 tcp_data_queue+0x25f2/0x4c90 net/ipv4/tcp_input.c:5057 tcp_rcv_state_process+0x1774/0x4e80 net/ipv4/tcp_input.c:6659 tcp_v4_do_rcv+0x339/0x980 net/ipv4/tcp_ipv4.c:1682 sk_backlog_rcv include/net/sock.h:1061 [inline] __release_sock+0x134/0x3b0 net/core/sock.c:2849 release_sock+0x54/0x1b0 net/core/sock.c:3404 inet_shutdown+0x1e0/0x430 net/ipv4/af_inet.c:909 __sys_shutdown_sock net/socket.c:2331 [inline] __sys_shutdown_sock net/socket.c:2325 [inline] __sys_shutdown+0xf1/0x1b0 net/socket.c:2343 __do_sys_shutdown net/socket.c:2351 [inline] __se_sys_shutdown net/socket.c:2349 [inline] __x64_sys_shutdown+0x50/0x70 net/socket.c:2349 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 During SMC fallback process in connect syscall, kernel will replaces TCP with SMC. In order to forward wakeup smc socket waitqueue after fallback, kernel will sets clcsk->sk_user_data to origin smc socket in smc_fback_replace_callbacks(). Later, in shutdown syscall, kernel will calls sk_psock_get(), which treats the clcsk->sk_user_data as psock type, triggering the refcnt warning. So, the root cause is that smc and psock, both will use sk_user_data field. So they will mismatch this field easily. This patch solves it by using another bit(defined as SK_USER_DATA_PSOCK) in PTRMASK, to mark whether sk_user_data points to a psock object or not. This patch depends on a PTRMASK introduced in commit f1ff5ce2cd5e ("net, sk_msg: Clear sk_user_data pointer on clone if tagged"). For there will possibly be more flags in the sk_user_data field, this patch also refactor sk_user_data flags code to be more generic to improve its maintainability. Reported-and-tested-by: syzbot+5f26f85569bd179c18ce@syzkaller.appspotmail.com Suggested-by: Jakub Kicinski Acked-by: Wen Gu Signed-off-by: Hawkins Jiawei --- v4 -> v5: - add more info about SK_USER_DATA_BPF in comment - correct the function definition format - generalize rcu_deference_sk_user_data_psock() into __rcu_deference_sk_user_data_with_flags() v3 -> v4: - change new subject - fix diff content, which has been edit accidentally v2 -> v3: - use SK_USER_DATA_PSOCK instead of SK_USER_DATA_NOTPSOCK to patch the bug - refactor the code on assigning to sk_user_data field in psock part - refactor the code on getting and setting the flag with sk_user_data field v1 -> v2: - add bit in PTRMASK to patch the bug include/linux/skmsg.h | 3 +- include/net/sock.h | 68 ++++++++++++++++++++++++++++++------------- net/core/skmsg.c | 4 ++- 3 files changed, 53 insertions(+), 22 deletions(-) diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h index c5a2d6f50f25..c5bdc5975a5c 100644 --- a/include/linux/skmsg.h +++ b/include/linux/skmsg.h @@ -277,7 +277,8 @@ static inline void sk_msg_sg_copy_clear(struct sk_msg *msg, u32 start) static inline struct sk_psock *sk_psock(const struct sock *sk) { - return rcu_dereference_sk_user_data(sk); + return __rcu_dereference_sk_user_data_with_flags(sk, + SK_USER_DATA_PSOCK); } static inline void sk_psock_set_state(struct sk_psock *psock, diff --git a/include/net/sock.h b/include/net/sock.h index 9fa54762e077..a5ebc3b28804 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -545,14 +545,26 @@ enum sk_pacing { SK_PACING_FQ = 2, }; -/* Pointer stored in sk_user_data might not be suitable for copying - * when cloning the socket. For instance, it can point to a reference - * counted object. sk_user_data bottom bit is set if pointer must not - * be copied. +/* flag bits in sk_user_data + * + * - SK_USER_DATA_NOCOPY: Pointer stored in sk_user_data might + * not be suitable for copying when cloning the socket. For instance, + * it can point to a reference counted object. sk_user_data bottom + * bit is set if pointer must not be copied. + * + * - SK_USER_DATA_BPF: Mark whether sk_user_data field is + * managed/owned by a BPF reuseport array. This bit should be set + * when sk_user_data's sk is added to the bpf's reuseport_array. + * + * - SK_USER_DATA_PSOCK: Mark whether pointer stored in + * sk_user_data points to psock type. This bit should be set + * when sk_user_data is assigned to a psock object. */ #define SK_USER_DATA_NOCOPY 1UL -#define SK_USER_DATA_BPF 2UL /* Managed by BPF */ -#define SK_USER_DATA_PTRMASK ~(SK_USER_DATA_NOCOPY | SK_USER_DATA_BPF) +#define SK_USER_DATA_BPF 2UL +#define SK_USER_DATA_PSOCK 4UL +#define SK_USER_DATA_PTRMASK ~(SK_USER_DATA_NOCOPY | SK_USER_DATA_BPF |\ + SK_USER_DATA_PSOCK) /** * sk_user_data_is_nocopy - Test if sk_user_data pointer must not be copied @@ -565,24 +577,40 @@ static inline bool sk_user_data_is_nocopy(const struct sock *sk) #define __sk_user_data(sk) ((*((void __rcu **)&(sk)->sk_user_data))) +/** + * __rcu_dereference_sk_user_data_with_flags - return the pointer + * only if argument flags all has been set in sk_user_data. Otherwise + * return NULL + * + * @sk: socket + * @flags: flag bits + */ +static inline void * +__rcu_dereference_sk_user_data_with_flags(const struct sock *sk, + uintptr_t flags) +{ + uintptr_t sk_user_data = (uintptr_t)rcu_dereference(__sk_user_data(sk)); + + WARN_ON_ONCE(flags & SK_USER_DATA_PTRMASK); + + if ((sk_user_data & flags) == flags) + return (void *)(sk_user_data & SK_USER_DATA_PTRMASK); + return NULL; +} + #define rcu_dereference_sk_user_data(sk) \ + __rcu_dereference_sk_user_data_with_flags(sk, 0) +#define __rcu_assign_sk_user_data_with_flags(sk, ptr, flags) \ ({ \ - void *__tmp = rcu_dereference(__sk_user_data((sk))); \ - (void *)((uintptr_t)__tmp & SK_USER_DATA_PTRMASK); \ -}) -#define rcu_assign_sk_user_data(sk, ptr) \ -({ \ - uintptr_t __tmp = (uintptr_t)(ptr); \ - WARN_ON_ONCE(__tmp & ~SK_USER_DATA_PTRMASK); \ - rcu_assign_pointer(__sk_user_data((sk)), __tmp); \ -}) -#define rcu_assign_sk_user_data_nocopy(sk, ptr) \ -({ \ - uintptr_t __tmp = (uintptr_t)(ptr); \ - WARN_ON_ONCE(__tmp & ~SK_USER_DATA_PTRMASK); \ + uintptr_t __tmp1 = (uintptr_t)(ptr), \ + __tmp2 = (uintptr_t)(flags); \ + WARN_ON_ONCE(__tmp1 & ~SK_USER_DATA_PTRMASK); \ + WARN_ON_ONCE(__tmp2 & SK_USER_DATA_PTRMASK); \ rcu_assign_pointer(__sk_user_data((sk)), \ - __tmp | SK_USER_DATA_NOCOPY); \ + __tmp1 | __tmp2); \ }) +#define rcu_assign_sk_user_data(sk, ptr) \ + __rcu_assign_sk_user_data_with_flags(sk, ptr, 0) static inline struct net *sock_net(const struct sock *sk) diff --git a/net/core/skmsg.c b/net/core/skmsg.c index b0fcd0200e84..10f7afa3d7a5 100644 --- a/net/core/skmsg.c +++ b/net/core/skmsg.c @@ -735,7 +735,9 @@ struct sk_psock *sk_psock_init(struct sock *sk, int node) sk_psock_set_state(psock, SK_PSOCK_TX_ENABLED); refcount_set(&psock->refcnt, 1); - rcu_assign_sk_user_data_nocopy(sk, psock); + __rcu_assign_sk_user_data_with_flags(sk, psock, + SK_USER_DATA_NOCOPY | + SK_USER_DATA_PSOCK); sock_hold(sk); out: