From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754975AbeE1RfN (ORCPT ); Mon, 28 May 2018 13:35:13 -0400 Received: from mail-io0-f200.google.com ([209.85.223.200]:41767 "EHLO mail-io0-f200.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754772AbeE1RfD (ORCPT ); Mon, 28 May 2018 13:35:03 -0400 X-Google-Smtp-Source: ADUXVKI038hIDaGsIaHREbVZI/8WlanpvcC6uSUuFc2LKeA0Bpt1nHg6fWQ43VMpJS3kPxOwZSFqKEeMFeqCTBLmoeLzLGMZtZxa MIME-Version: 1.0 Date: Mon, 28 May 2018 10:35:02 -0700 In-Reply-To: <000000000000ca8a42056d4530a5@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <0000000000009f3a1b056d478948@google.com> Subject: Re: possible deadlock in bpf_tcp_close From: syzbot To: ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8"; format=flowed; delsp=yes Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org syzbot has found a reproducer for the following crash on: HEAD commit: 7a1a98c171ea Merge branch 'bpf-sendmsg-hook' git tree: bpf-next console output: https://syzkaller.appspot.com/x/log.txt?x=149ae2b7800000 kernel config: https://syzkaller.appspot.com/x/.config?x=e4078980b886800c dashboard link: https://syzkaller.appspot.com/bug?extid=47ed903f50684f046b15 compiler: gcc (GCC) 8.0.1 20180413 (experimental) syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=1553b17b800000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1460be2f800000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+47ed903f50684f046b15@syzkaller.appspotmail.com random: sshd: uninitialized urandom read (32 bytes read) random: sshd: uninitialized urandom read (32 bytes read) random: sshd: uninitialized urandom read (32 bytes read) ====================================================== WARNING: possible circular locking dependency detected 4.17.0-rc6+ #25 Not tainted ------------------------------------------------------ syz-executor800/4527 is trying to acquire lock: (ptrval) (&htab->buckets[i].lock){+...}, at: bpf_tcp_close+0x822/0x10b0 kernel/bpf/sockmap.c:285 but task is already holding lock: (ptrval) (clock-AF_INET6){++..}, at: bpf_tcp_close+0x241/0x10b0 kernel/bpf/sockmap.c:260 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (clock-AF_INET6){++..}: __raw_write_lock_bh include/linux/rwlock_api_smp.h:203 [inline] _raw_write_lock_bh+0x31/0x40 kernel/locking/spinlock.c:312 sock_hash_delete_elem+0x7c6/0xaf0 kernel/bpf/sockmap.c:2338 map_delete_elem+0x32e/0x4e0 kernel/bpf/syscall.c:815 __do_sys_bpf kernel/bpf/syscall.c:2349 [inline] __se_sys_bpf kernel/bpf/syscall.c:2317 [inline] __x64_sys_bpf+0x342/0x510 kernel/bpf/syscall.c:2317 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&htab->buckets[i].lock){+...}: lock_acquire+0x1dc/0x520 kernel/locking/lockdep.c:3920 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline] _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:168 bpf_tcp_close+0x822/0x10b0 kernel/bpf/sockmap.c:285 inet_release+0x104/0x1f0 net/ipv4/af_inet.c:427 inet6_release+0x50/0x70 net/ipv6/af_inet6.c:459 sock_release+0x96/0x1b0 net/socket.c:594 sock_close+0x16/0x20 net/socket.c:1149 __fput+0x34d/0x890 fs/file_table.c:209 ____fput+0x15/0x20 fs/file_table.c:243 task_work_run+0x1e4/0x290 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x1aee/0x2730 kernel/exit.c:865 do_group_exit+0x16f/0x430 kernel/exit.c:968 get_signal+0x886/0x1960 kernel/signal.c:2482 do_signal+0x98/0x2040 arch/x86/kernel/signal.c:810 exit_to_usermode_loop+0x28a/0x310 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline] syscall_return_slowpath arch/x86/entry/common.c:265 [inline] do_syscall_64+0x6ac/0x800 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(clock-AF_INET6); lock(&htab->buckets[i].lock); lock(clock-AF_INET6); lock(&htab->buckets[i].lock); *** DEADLOCK *** 2 locks held by syz-executor800/4527: #0: (ptrval) (rcu_read_lock){....}, at: bpf_tcp_close+0x0/0x10b0 kernel/bpf/sockmap.c:2106 #1: (ptrval) (clock-AF_INET6){++..}, at: bpf_tcp_close+0x241/0x10b0 kernel/bpf/sockmap.c:260 stack backtrace: CPU: 0 PID: 4527 Comm: syz-executor800 Not tainted 4.17.0-rc6+ #25 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+0x1b9/0x294 lib/dump_stack.c:113 print_circular_bug.isra.36.cold.54+0x1bd/0x27d kernel/locking/lockdep.c:1223 check_prev_add kernel/locking/lockdep.c:1863 [inline] check_prevs_add kernel/locking/lockdep.c:1976 [inline] validate_chain kernel/locking/lockdep.c:2417 [inline] __lock_acquire+0x343e/0x5140 kernel/locking/lockdep.c:3431 lock_acquire+0x1dc/0x520 kernel/locking/lockdep.c:3920 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline] _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:168 bpf_tcp_close+0x822/0x10b0 kernel/bpf/sockmap.c:285 inet_release+0x104/0x1f0 net/ipv4/af_inet.c:427 inet6_release+0x50/0x70 net/ipv6/af_inet6.c:459 sock_release+0x96/0x1b0 net/socket.c:594 sock_close+0x16/0x20 net/socket.c:1149 __fput+0x34d/0x890 fs/file_table.c:209 ____fput+0x15/0x20 fs/file_table.c:243 task_work_run+0x1e4/0x290 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x1aee/0x2730 kernel/exit.c:865 do_group_exit+0x16f/0x430 kernel/exit.c:968 get_signal+0x886/0x1960 kernel/signal.c:2482 do_signal+0x98/0x2040 arch/x86/kernel/signal.c:810 exit_to_usermode_loop+0x28a/0x310 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline] syscall_return_slowpath arch/x86/entry/common.c:265 [inline] do_syscall_64+0x6ac/0x800 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x445709 RSP: 002b:00007f36c605ddb8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00000000006dac3c RCX: 0000000000445709 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000006dac3c RBP: 00000000006dac38 R08: 0000000000000000 R09: 000