From patchwork Thu Oct 20 22:45:12 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Dumazet X-Patchwork-Id: 13014082 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 8B1FCC433FE for ; Thu, 20 Oct 2022 22:45:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230129AbiJTWpw (ORCPT ); Thu, 20 Oct 2022 18:45:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44694 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230173AbiJTWpY (ORCPT ); Thu, 20 Oct 2022 18:45:24 -0400 Received: from mail-qt1-x84a.google.com (mail-qt1-x84a.google.com [IPv6:2607:f8b0:4864:20::84a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B25C2F4196 for ; Thu, 20 Oct 2022 15:45:19 -0700 (PDT) Received: by mail-qt1-x84a.google.com with SMTP id 22-20020ac85756000000b0039cf0d41e2cso639474qtx.13 for ; Thu, 20 Oct 2022 15:45:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=MJVY2U/gLkRLqk7c9Krx7oI5gjbx3/ytC15tm+5mQZA=; b=qNP1zcNv3HZIG2nRpRwJ7LGD0VEG/zVjtw4nEFcsze+M7V03JYsZcAZ38BvRtSqQsU K3oYxP8ATCTE7pZD4kULaGZ+6pVtW/xiImmUjmpliMHvxFHFTyl+YOl8SgaSgKuQckvi 8wofhDkzOFzM8icT6gHHaWyNyz7zk54MfoZeKdaRZOORSLqbwuD7u2nKRwehEjwEg/l+ BvV1IsI8DilGjTG1QTCNqb87FqcBthnl34A1X2dQ+8UXiCsr7lmmQJ7FykS7dOXZQ/K/ CDSEaVPNm1orQ0T1zYWRcxIxL0p8wBgm8nuqa59heIOFei9Gv/aUrJE9QR2zXbj1TkKT 1Wsw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=MJVY2U/gLkRLqk7c9Krx7oI5gjbx3/ytC15tm+5mQZA=; b=sRSVEHYGTBMYxFAovUkWh7vlK8ZrIXpNCUZwbmlEozdPvHo1aLsmTQ3V85Nh1GQNYH 2JSy9TG6VRHsrLgMf/hQ46UTpYizxr3E9G0kHbiPn7ToPbU+2X3xmokVW0JK6SwezJx7 AHiU2r9NYUi+Alnvu8hFgC6NmIYZ4sBEX+5HsBDbR/0LKagX9axzwbxieg3tiQA0ALh+ 79L/8R/SGr1/0FMz04GK5hvf1ovpRoSnhwcsOy3Bu2wLv/q/Kx07i4gx6I5AKyhRisQR hwX44ris/q0DnucexI7QA5ZYNJNa3O28gxWUtYCwfXqP6oEsAMgiR2DMrZrMP8uPX+LF 94SA== X-Gm-Message-State: ACrzQf0GlH/ENfW5dysGbPgnbE06/UnAYdF1u8TaHj39kmFVSD5lrzm3 jSVRiTBvmnN2/YDr+l0ojgCYLbL5HlErmQ== X-Google-Smtp-Source: AMsMyM4bVA1XhvKyLbbVpTX+OF+57gKeo5MU4Pqy91wUFM+Pv9mCRkdJwPHJgy4uTxlLxvGQaZCCJukCyP4j6w== X-Received: from edumazet1.c.googlers.com ([fda3:e722:ac3:cc00:2b:7d90:c0a8:395a]) (user=edumazet job=sendgmr) by 2002:a05:6214:1c0c:b0:4b1:d2fe:7ad4 with SMTP id u12-20020a0562141c0c00b004b1d2fe7ad4mr13904090qvc.128.1666305918606; Thu, 20 Oct 2022 15:45:18 -0700 (PDT) Date: Thu, 20 Oct 2022 22:45:12 +0000 In-Reply-To: <20221020224512.3211657-1-edumazet@google.com> Mime-Version: 1.0 References: <20221020224512.3211657-1-edumazet@google.com> X-Mailer: git-send-email 2.38.0.135.g90850a2211-goog Message-ID: <20221020224512.3211657-3-edumazet@google.com> Subject: [PATCH net 2/2] kcm: annotate data-races around kcm->rx_wait From: Eric Dumazet To: "David S . Miller" , Jakub Kicinski , Paolo Abeni Cc: netdev@vger.kernel.org, eric.dumazet@gmail.com, Eric Dumazet , syzbot Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org kcm->rx_psock can be read locklessly in kcm_rfree(). Annotate the read and writes accordingly. syzbot reported: BUG: KCSAN: data-race in kcm_rcv_strparser / kcm_rfree write to 0xffff88810784e3d0 of 1 bytes by task 1823 on cpu 1: reserve_rx_kcm net/kcm/kcmsock.c:283 [inline] kcm_rcv_strparser+0x250/0x3a0 net/kcm/kcmsock.c:363 __strp_recv+0x64c/0xd20 net/strparser/strparser.c:301 strp_recv+0x6d/0x80 net/strparser/strparser.c:335 tcp_read_sock+0x13e/0x5a0 net/ipv4/tcp.c:1703 strp_read_sock net/strparser/strparser.c:358 [inline] do_strp_work net/strparser/strparser.c:406 [inline] strp_work+0xe8/0x180 net/strparser/strparser.c:415 process_one_work+0x3d3/0x720 kernel/workqueue.c:2289 worker_thread+0x618/0xa70 kernel/workqueue.c:2436 kthread+0x1a9/0x1e0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 read to 0xffff88810784e3d0 of 1 bytes by task 17869 on cpu 0: kcm_rfree+0x121/0x220 net/kcm/kcmsock.c:181 skb_release_head_state+0x8e/0x160 net/core/skbuff.c:841 skb_release_all net/core/skbuff.c:852 [inline] __kfree_skb net/core/skbuff.c:868 [inline] kfree_skb_reason+0x5c/0x260 net/core/skbuff.c:891 kfree_skb include/linux/skbuff.h:1216 [inline] kcm_recvmsg+0x226/0x2b0 net/kcm/kcmsock.c:1161 ____sys_recvmsg+0x16c/0x2e0 ___sys_recvmsg net/socket.c:2743 [inline] do_recvmmsg+0x2f1/0x710 net/socket.c:2837 __sys_recvmmsg net/socket.c:2916 [inline] __do_sys_recvmmsg net/socket.c:2939 [inline] __se_sys_recvmmsg net/socket.c:2932 [inline] __x64_sys_recvmmsg+0xde/0x160 net/socket.c:2932 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd value changed: 0x01 -> 0x00 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 17869 Comm: syz-executor.2 Not tainted 6.1.0-rc1-syzkaller-00010-gbb1a1146467a-dirty #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022 Fixes: ab7ac4eb9832 ("kcm: Kernel Connection Multiplexor module") Reported-by: syzbot Signed-off-by: Eric Dumazet --- net/kcm/kcmsock.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c index 0109ef6ddf9aed853a6cf1fb69e330fd8bc6654a..63e32f181f435334530c42e54c7a36e8e993104b 100644 --- a/net/kcm/kcmsock.c +++ b/net/kcm/kcmsock.c @@ -162,7 +162,8 @@ static void kcm_rcv_ready(struct kcm_sock *kcm) /* Buffer limit is okay now, add to ready list */ list_add_tail(&kcm->wait_rx_list, &kcm->mux->kcm_rx_waiters); - kcm->rx_wait = true; + /* paired with lockless reads in kcm_rfree() */ + WRITE_ONCE(kcm->rx_wait, true); } static void kcm_rfree(struct sk_buff *skb) @@ -178,7 +179,7 @@ static void kcm_rfree(struct sk_buff *skb) /* For reading rx_wait and rx_psock without holding lock */ smp_mb__after_atomic(); - if (!kcm->rx_wait && !READ_ONCE(kcm->rx_psock) && + if (!READ_ONCE(kcm->rx_wait) && !READ_ONCE(kcm->rx_psock) && sk_rmem_alloc_get(sk) < sk->sk_rcvlowat) { spin_lock_bh(&mux->rx_lock); kcm_rcv_ready(kcm); @@ -237,7 +238,8 @@ static void requeue_rx_msgs(struct kcm_mux *mux, struct sk_buff_head *head) if (kcm_queue_rcv_skb(&kcm->sk, skb)) { /* Should mean socket buffer full */ list_del(&kcm->wait_rx_list); - kcm->rx_wait = false; + /* paired with lockless reads in kcm_rfree() */ + WRITE_ONCE(kcm->rx_wait, false); /* Commit rx_wait to read in kcm_free */ smp_wmb(); @@ -280,7 +282,8 @@ static struct kcm_sock *reserve_rx_kcm(struct kcm_psock *psock, kcm = list_first_entry(&mux->kcm_rx_waiters, struct kcm_sock, wait_rx_list); list_del(&kcm->wait_rx_list); - kcm->rx_wait = false; + /* paired with lockless reads in kcm_rfree() */ + WRITE_ONCE(kcm->rx_wait, false); psock->rx_kcm = kcm; /* paired with lockless reads in kcm_rfree() */ @@ -1242,7 +1245,8 @@ static void kcm_recv_disable(struct kcm_sock *kcm) if (!kcm->rx_psock) { if (kcm->rx_wait) { list_del(&kcm->wait_rx_list); - kcm->rx_wait = false; + /* paired with lockless reads in kcm_rfree() */ + WRITE_ONCE(kcm->rx_wait, false); } requeue_rx_msgs(mux, &kcm->sk.sk_receive_queue); @@ -1795,7 +1799,8 @@ static void kcm_done(struct kcm_sock *kcm) if (kcm->rx_wait) { list_del(&kcm->wait_rx_list); - kcm->rx_wait = false; + /* paired with lockless reads in kcm_rfree() */ + WRITE_ONCE(kcm->rx_wait, false); } /* Move any pending receive messages to other kcm sockets */ requeue_rx_msgs(mux, &sk->sk_receive_queue);