From patchwork Wed Mar 11 18:44:26 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Dumazet X-Patchwork-Id: 1253140 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20161025 header.b=kU90F5eA; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 48d18d3JNFz9s3x for ; Thu, 12 Mar 2020 05:44:33 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730781AbgCKSob (ORCPT ); Wed, 11 Mar 2020 14:44:31 -0400 Received: from mail-pl1-f202.google.com ([209.85.214.202]:48182 "EHLO mail-pl1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730730AbgCKSob (ORCPT ); Wed, 11 Mar 2020 14:44:31 -0400 Received: by mail-pl1-f202.google.com with SMTP id w3so1730445plz.15 for ; Wed, 11 Mar 2020 11:44:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc; bh=V5utLIEDzwq7LeSAtItzmD1JbNLw+JdXcL3i+r4+PIw=; b=kU90F5eAQz5fez5zWVccHoOVyWRnW4KOO3uLCP2ubjkPTUyL2PBnucXVpLyVEi0hCc q3Z2zIEUyTTUqFMsvoYYWMCkkKrC7bvpON6KLcIedhYnYTo9dMkFGryBjFxS1izqjxsV yA4ePJj3b58lDzmXQo9UUUcVeXJJ4+sPfve0Mb7ZvjnpXQprDdPoKlOZ/Mc+HRCghi79 JfBsLJmU/YfWy7wxZPoxhNU/juL+FD8pbgZCKajS4rjstIBl2UTKAzSORjfcmqMnfOZK X8tDs9KiEUbGoBbH/ZOLmgjgAlZIgVLzR/xp18Y1u0s7wpu+2fyfW3PB37dqadSoeZ+h LMEA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=V5utLIEDzwq7LeSAtItzmD1JbNLw+JdXcL3i+r4+PIw=; b=t0viqPRf4xPzJ1UIT+Qt9U2MP3kgKrXfKxmPywh8jCBxKmiKWvw+n9iFs8DD/6cUGh si+XP4DZedrDAalQtVOAxPgT5Hlafn0hEfiBoRCyjaUq1LsICpeNt1I2AePPfv3qWcyH undQ9dD4H8rYyDDTWU2UAQ7e9pZHS2nbtJQFW+K5Ehg0Gpshn6T6kEXDlQFfGQV8H/TM imSo5JP+RS9pqIUrjiA6B+0rQzeKEzmZ+nTklDH4Lw6Kb5swiySLB/05eAQV7fCDzKjd c2xM7VhNHcQExxzSv/mKEhiGTU2fhLfgeUdw4RcC1FA/GRxSVcZIssOHTQy8fhWoKSKc U6oA== X-Gm-Message-State: ANhLgQ1TIjUUnqwJYWuLMSC/dqACG1lzy1haHsDWoGHXN1OkLqtVroY4 /K9vvJT3WyuYcxYaz4jvQZbpp46pkjiXXQ== X-Google-Smtp-Source: ADFU+vu7mFtXHGnHrfHjHWq7ncN2EOE1bJAFRqyVmZvUuhZ2Q3h84j4bS177C8CIjeJoq8QbNuGSRJWa2x/5xg== X-Received: by 2002:a17:90a:37ea:: with SMTP id v97mr155200pjb.26.1583952269664; Wed, 11 Mar 2020 11:44:29 -0700 (PDT) Date: Wed, 11 Mar 2020 11:44:26 -0700 Message-Id: <20200311184426.39253-1-edumazet@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.25.1.481.gfbce0eb801-goog Subject: [PATCH net] net: memcg: fix lockdep splat in inet_csk_accept() From: Eric Dumazet To: "David S . Miller" Cc: netdev , Eric Dumazet , Eric Dumazet , Shakeel Butt , syzbot Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Locking newsk while still holding the listener lock triggered a lockdep splat [1] We can simply move the memcg code after we release the listener lock, as this can also help if multiple threads are sharing a common listener. Also fix a typo while reading socket sk_rmem_alloc. [1] WARNING: possible recursive locking detected 5.6.0-rc3-syzkaller #0 Not tainted -------------------------------------------- syz-executor598/9524 is trying to acquire lock: ffff88808b5b8b90 (sk_lock-AF_INET6){+.+.}, at: lock_sock include/net/sock.h:1541 [inline] ffff88808b5b8b90 (sk_lock-AF_INET6){+.+.}, at: inet_csk_accept+0x69f/0xd30 net/ipv4/inet_connection_sock.c:492 but task is already holding lock: ffff88808b5b9590 (sk_lock-AF_INET6){+.+.}, at: lock_sock include/net/sock.h:1541 [inline] ffff88808b5b9590 (sk_lock-AF_INET6){+.+.}, at: inet_csk_accept+0x8d/0xd30 net/ipv4/inet_connection_sock.c:445 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(sk_lock-AF_INET6); lock(sk_lock-AF_INET6); *** DEADLOCK *** May be due to missing lock nesting notation 1 lock held by syz-executor598/9524: #0: ffff88808b5b9590 (sk_lock-AF_INET6){+.+.}, at: lock_sock include/net/sock.h:1541 [inline] #0: ffff88808b5b9590 (sk_lock-AF_INET6){+.+.}, at: inet_csk_accept+0x8d/0xd30 net/ipv4/inet_connection_sock.c:445 stack backtrace: CPU: 0 PID: 9524 Comm: syz-executor598 Not tainted 5.6.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x188/0x20d lib/dump_stack.c:118 print_deadlock_bug kernel/locking/lockdep.c:2370 [inline] check_deadlock kernel/locking/lockdep.c:2411 [inline] validate_chain kernel/locking/lockdep.c:2954 [inline] __lock_acquire.cold+0x114/0x288 kernel/locking/lockdep.c:3954 lock_acquire+0x197/0x420 kernel/locking/lockdep.c:4484 lock_sock_nested+0xc5/0x110 net/core/sock.c:2947 lock_sock include/net/sock.h:1541 [inline] inet_csk_accept+0x69f/0xd30 net/ipv4/inet_connection_sock.c:492 inet_accept+0xe9/0x7c0 net/ipv4/af_inet.c:734 __sys_accept4_file+0x3ac/0x5b0 net/socket.c:1758 __sys_accept4+0x53/0x90 net/socket.c:1809 __do_sys_accept4 net/socket.c:1821 [inline] __se_sys_accept4 net/socket.c:1818 [inline] __x64_sys_accept4+0x93/0xf0 net/socket.c:1818 do_syscall_64+0xf6/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4445c9 Code: e8 0c 0d 03 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 eb 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffc35b37608 EFLAGS: 00000246 ORIG_RAX: 0000000000000120 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004445c9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000306777 R09: 0000000000306777 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00000000004053d0 R14: 0000000000000000 R15: 0000000000000000 Fixes: d752a4986532 ("net: memcg: late association of sock to memcg") Signed-off-by: Eric Dumazet Cc: Shakeel Butt Reported-by: syzbot --- net/ipv4/inet_connection_sock.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index 65a3b2565102622e9c87fb4342dcb6f583c1c37e..d545fb99a8a1c84153c4a42226d15754c1f52ca0 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -483,27 +483,27 @@ struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern) spin_unlock_bh(&queue->fastopenq.lock); } - if (mem_cgroup_sockets_enabled) { +out: + release_sock(sk); + if (newsk && mem_cgroup_sockets_enabled) { int amt; /* atomically get the memory usage, set and charge the - * sk->sk_memcg. + * newsk->sk_memcg. */ lock_sock(newsk); - /* The sk has not been accepted yet, no need to look at - * sk->sk_wmem_queued. + /* The socket has not been accepted yet, no need to look at + * newsk->sk_wmem_queued. */ amt = sk_mem_pages(newsk->sk_forward_alloc + - atomic_read(&sk->sk_rmem_alloc)); + atomic_read(&newsk->sk_rmem_alloc)); mem_cgroup_sk_alloc(newsk); if (newsk->sk_memcg && amt) mem_cgroup_charge_skmem(newsk->sk_memcg, amt); release_sock(newsk); } -out: - release_sock(sk); if (req) reqsk_put(req); return newsk;