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 X-Spam-Level: X-Spam-Status: No, score=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D366BC48BE6 for ; Wed, 16 Jun 2021 13:42:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B992F611EE for ; Wed, 16 Jun 2021 13:42:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232684AbhFPNoe (ORCPT ); Wed, 16 Jun 2021 09:44:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42740 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233375AbhFPNod (ORCPT ); Wed, 16 Jun 2021 09:44:33 -0400 Received: from mail-pg1-x52c.google.com (mail-pg1-x52c.google.com [IPv6:2607:f8b0:4864:20::52c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 43C24C061574 for ; Wed, 16 Jun 2021 06:42:27 -0700 (PDT) Received: by mail-pg1-x52c.google.com with SMTP id i34so1985066pgl.9 for ; Wed, 16 Jun 2021 06:42:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=FhTyZ1cXYSs6bORtOYAkFXifoja7i8pW27ktzI2Fid4=; b=BElRxcr4Wtf9GWI7fjTug2kfMPnPXVwYd/eiTIhm9Gd5VrvRsMLOTe+l8ax278pUXT 9Xojcv+wPipiAdOj1RqzFHMd2eraAxEBDFc8idfnJU8cKQysfVQMpcoxTN4/AihjS7Bz vAx0LcEYFMVNbzRWxSECm7GSO1Zw/VoGKahGT6fiFVZ9j430nI5O66jQB9NqsUXnlTpw sxZvo/iCxVs4/M0F307eR10LzUoImSBziPETHGUrwrLm6+nNxVe9StWcK+zgDvQil1eI rl9SbmMAANMzLlVXjBU3DAnWyoVqZIykztBO+4ZNd5Z22MyQyXEm06OUfkpw0ScfE61T zHKA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=FhTyZ1cXYSs6bORtOYAkFXifoja7i8pW27ktzI2Fid4=; b=pSfVxMdrC4aQosyvF9pRri/wTOb79VgplM7qi/Rvst1UiXWGk5l4iOVRCgAe6fjnkt Xlx7a2N9qUIwvgEjj6eeI1x5QKLLCvpnu1yNtNY6o59D3Te1QiU0nU/1jy7XTqs6F5oM tYcBlKNR7uqD7AqJwjqWiltXGLfuy0zTzKXzfP3jHK7hgGim0+yI0boV1hi31Fc0oB3N pswmHXafoowxngG3UdDZs6joxvwvKq58zHj0BR53whcvjlL8S7mF085sTXp8vCvQm9hQ WhJi4xOZsZY/qXNm21b0ZMM+ukyCHbxnEm5Vv0YYeRvWSeA5E+P3Y/zOe7axY1sF8rgp nuMA== X-Gm-Message-State: AOAM531DWPk4nu8h0mYYqk7F0N1M/sdm0H4m1I40egtCHa89d+MQltcF FXhacdPmhjCgAE6M2tS8dCc= X-Google-Smtp-Source: ABdhPJyPc+PPt6CmY60YRXL6NAcvmqBrRxA2u+oC9du2TrdrQ+7p9RZqnErUnoQYn6XQWCYcKz/jFQ== X-Received: by 2002:a63:ff22:: with SMTP id k34mr5074059pgi.336.1623850946863; Wed, 16 Jun 2021 06:42:26 -0700 (PDT) Received: from edumazet1.svl.corp.google.com ([2620:15c:2c4:201:e857:405b:92df:8194]) by smtp.gmail.com with ESMTPSA id e6sm5764467pjl.3.2021.06.16.06.42.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Jun 2021 06:42:26 -0700 (PDT) From: Eric Dumazet To: "David S . Miller" , Jakub Kicinski Cc: netdev , Eric Dumazet , Eric Dumazet , syzbot Subject: [PATCH net 1/2] net/packet: annotate accesses to po->bind Date: Wed, 16 Jun 2021 06:42:01 -0700 Message-Id: <20210616134202.3661456-2-eric.dumazet@gmail.com> X-Mailer: git-send-email 2.32.0.272.g935e593368-goog In-Reply-To: <20210616134202.3661456-1-eric.dumazet@gmail.com> References: <20210616134202.3661456-1-eric.dumazet@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Eric Dumazet tpacket_snd(), packet_snd(), packet_getname() and packet_seq_show() can read po->num without holding a lock. This means other threads can change po->num at the same time. KCSAN complained about this known fact [1] Add READ_ONCE()/WRITE_ONCE() to address the issue. [1] BUG: KCSAN: data-race in packet_do_bind / packet_sendmsg write to 0xffff888131a0dcc0 of 2 bytes by task 24714 on cpu 0: packet_do_bind+0x3ab/0x7e0 net/packet/af_packet.c:3181 packet_bind+0xc3/0xd0 net/packet/af_packet.c:3255 __sys_bind+0x200/0x290 net/socket.c:1637 __do_sys_bind net/socket.c:1648 [inline] __se_sys_bind net/socket.c:1646 [inline] __x64_sys_bind+0x3d/0x50 net/socket.c:1646 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae read to 0xffff888131a0dcc0 of 2 bytes by task 24719 on cpu 1: packet_snd net/packet/af_packet.c:2899 [inline] packet_sendmsg+0x317/0x3570 net/packet/af_packet.c:3040 sock_sendmsg_nosec net/socket.c:654 [inline] sock_sendmsg net/socket.c:674 [inline] ____sys_sendmsg+0x360/0x4d0 net/socket.c:2350 ___sys_sendmsg net/socket.c:2404 [inline] __sys_sendmsg+0x1ed/0x270 net/socket.c:2433 __do_sys_sendmsg net/socket.c:2442 [inline] __se_sys_sendmsg net/socket.c:2440 [inline] __x64_sys_sendmsg+0x42/0x50 net/socket.c:2440 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae value changed: 0x0000 -> 0x1200 Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 24719 Comm: syz-executor.5 Not tainted 5.13.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Signed-off-by: Eric Dumazet Reported-by: syzbot --- net/packet/af_packet.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 74e6e45a8e8435a556ce813c410a1f4146dd05b6..e91a36bdd1abaf18a679b914ae0d722d42c9369b 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2683,7 +2683,7 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg) } if (likely(saddr == NULL)) { dev = packet_cached_dev_get(po); - proto = po->num; + proto = READ_ONCE(po->num); } else { err = -EINVAL; if (msg->msg_namelen < sizeof(struct sockaddr_ll)) @@ -2896,7 +2896,7 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len) if (likely(saddr == NULL)) { dev = packet_cached_dev_get(po); - proto = po->num; + proto = READ_ONCE(po->num); } else { err = -EINVAL; if (msg->msg_namelen < sizeof(struct sockaddr_ll)) @@ -3171,7 +3171,7 @@ static int packet_do_bind(struct sock *sk, const char *name, int ifindex, /* prevents packet_notifier() from calling * register_prot_hook() */ - po->num = 0; + WRITE_ONCE(po->num, 0); __unregister_prot_hook(sk, true); rcu_read_lock(); dev_curr = po->prot_hook.dev; @@ -3181,7 +3181,7 @@ static int packet_do_bind(struct sock *sk, const char *name, int ifindex, } BUG_ON(po->running); - po->num = proto; + WRITE_ONCE(po->num, proto); po->prot_hook.type = proto; if (unlikely(unlisted)) { @@ -3526,7 +3526,7 @@ static int packet_getname(struct socket *sock, struct sockaddr *uaddr, sll->sll_family = AF_PACKET; sll->sll_ifindex = po->ifindex; - sll->sll_protocol = po->num; + sll->sll_protocol = READ_ONCE(po->num); sll->sll_pkttype = 0; rcu_read_lock(); dev = dev_get_by_index_rcu(sock_net(sk), po->ifindex); @@ -4414,7 +4414,7 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u, was_running = po->running; num = po->num; if (was_running) { - po->num = 0; + WRITE_ONCE(po->num, 0); __unregister_prot_hook(sk, false); } spin_unlock(&po->bind_lock); @@ -4449,7 +4449,7 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u, spin_lock(&po->bind_lock); if (was_running) { - po->num = num; + WRITE_ONCE(po->num, num); register_prot_hook(sk); } spin_unlock(&po->bind_lock); @@ -4619,7 +4619,7 @@ static int packet_seq_show(struct seq_file *seq, void *v) s, refcount_read(&s->sk_refcnt), s->sk_type, - ntohs(po->num), + ntohs(READ_ONCE(po->num)), po->ifindex, po->running, atomic_read(&s->sk_rmem_alloc), -- 2.32.0.272.g935e593368-goog