Re: suspicious RCU usage at ./include/net/inet_sock.h:LINE

[Dmitry Vyukov]

On Sun, Nov 5, 2017 at 11:35 AM, syzbot
<bot+79de6f09efc55fec084b706de3c91e9457433ac5@xxxxxxxxxxxxxxxxxxxxxxxxx>
wrote:
> Hello,
>
> syzkaller hit the following crash on
> 5a3517e009e979f21977d362212b7729c5165d92
> git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
> compiler: gcc (GCC) 7.1.1 20170620
> .config is attached
> Raw console output is attached.
>
>
>
>
>
> =============================
> WARNING: suspicious RCU usage
> 4.14.0-rc7-next-20171103+ #10 Not tainted
> -----------------------------
> ./include/net/inet_sock.h:136 suspicious rcu_dereference_check() usage!
>
> other info that might help us debug this:
>
>
> rcu_scheduler_active = 2, debug_locks = 1
> 1 lock held by syz-executor0/836:
>  #0:  (sk_lock-AF_INET6){+.+.}, at: [<ffffffff840fe133>] lock_sock
> include/net/sock.h:1461 [inline]
>  #0:  (sk_lock-AF_INET6){+.+.}, at: [<ffffffff840fe133>]
> sock_setsockopt+0x163/0x1ae0 net/core/sock.c:715
>
> stack backtrace:
> CPU: 0 PID: 836 Comm: syz-executor0 Not tainted 4.14.0-rc7-next-20171103+
> #10
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:17 [inline]
>  dump_stack+0x194/0x257 lib/dump_stack.c:53
>  lockdep_rcu_suspicious+0x123/0x170 kernel/locking/lockdep.c:4675
>  ireq_opt_deref include/net/inet_sock.h:135 [inline]
>  inet_csk_route_req+0x82a/0xca0 net/ipv4/inet_connection_sock.c:544
>  dccp_v4_send_response+0xa7/0x640 net/dccp/ipv4.c:485
>  dccp_v4_conn_request+0x9f4/0x11b0 net/dccp/ipv4.c:633
>  dccp_v6_conn_request+0xd30/0x1350 net/dccp/ipv6.c:317
>  dccp_rcv_state_process+0x574/0x1620 net/dccp/input.c:612
>  dccp_v4_do_rcv+0xeb/0x160 net/dccp/ipv4.c:682
>  dccp_v6_do_rcv+0x81a/0x9b0 net/dccp/ipv6.c:578
>  sk_backlog_rcv include/net/sock.h:909 [inline]
>  __release_sock+0x124/0x360 net/core/sock.c:2264
>  release_sock+0xa4/0x2a0 net/core/sock.c:2776
>  sock_setsockopt+0x513/0x1ae0 net/core/sock.c:1066
>  SYSC_setsockopt net/socket.c:1847 [inline]
>  SyS_setsockopt+0x2ff/0x360 net/socket.c:1830
>  entry_SYSCALL_64_fastpath+0x1f/0xbe
> RIP: 0033:0x447c89
> RSP: 002b:00007f86cc482bd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
> RAX: ffffffffffffffda RBX: 00007f86cc4836cc RCX: 0000000000447c89
> RDX: 000000000000001a RSI: 0000000000000001 RDI: 0000000000000013
> RBP: 0000000000000086 R08: 0000000000000010 R09: 0000000000000000
> R10: 0000000020c3a000 R11: 0000000000000246 R12: 00000000ffffffff
> R13: 00000000000006c0 R14: 00000000006e4760 R15: 00007f86cc483700
>
> =============================
> WARNING: suspicious RCU usage
> 4.14.0-rc7-next-20171103+ #10 Not tainted
> -----------------------------
> ./include/net/inet_sock.h:136 suspicious rcu_dereference_check() usage!
>
> other info that might help us debug this:
>
>
> rcu_scheduler_active = 2, debug_locks = 1
> 1 lock held by syz-executor0/836:
>  #0:  (sk_lock-AF_INET6){+.+.}, at: [<ffffffff840fe133>] lock_sock
> include/net/sock.h:1461 [inline]
>  #0:  (sk_lock-AF_INET6){+.+.}, at: [<ffffffff840fe133>]
> sock_setsockopt+0x163/0x1ae0 net/core/sock.c:715
>
> stack backtrace:
> CPU: 0 PID: 836 Comm: syz-executor0 Not tainted 4.14.0-rc7-next-20171103+
> #10
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:17 [inline]
>  dump_stack+0x194/0x257 lib/dump_stack.c:53
>  lockdep_rcu_suspicious+0x123/0x170 kernel/locking/lockdep.c:4675
>  ireq_opt_deref include/net/inet_sock.h:135 [inline]
>  dccp_v4_send_response+0x4b0/0x640 net/dccp/ipv4.c:496
>  dccp_v4_conn_request+0x9f4/0x11b0 net/dccp/ipv4.c:633
>  dccp_v6_conn_request+0xd30/0x1350 net/dccp/ipv6.c:317
>  dccp_rcv_state_process+0x574/0x1620 net/dccp/input.c:612
>  dccp_v4_do_rcv+0xeb/0x160 net/dccp/ipv4.c:682
>  dccp_v6_do_rcv+0x81a/0x9b0 net/dccp/ipv6.c:578
>  sk_backlog_rcv include/net/sock.h:909 [inline]
>  __release_sock+0x124/0x360 net/core/sock.c:2264
>  release_sock+0xa4/0x2a0 net/core/sock.c:2776
>  sock_setsockopt+0x513/0x1ae0 net/core/sock.c:1066
>  SYSC_setsockopt net/socket.c:1847 [inline]
>  SyS_setsockopt+0x2ff/0x360 net/socket.c:1830
>  entry_SYSCALL_64_fastpath+0x1f/0xbe
> RIP: 0033:0x447c89
> RSP: 002b:00007f86cc482bd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
> RAX: ffffffffffffffda RBX: 00007f86cc4836cc RCX: 0000000000447c89
> RDX: 000000000000001a RSI: 0000000000000001 RDI: 0000000000000013
> RBP: 0000000000000086 R08: 0000000000000010 R09: 0000000000000000
> R10: 0000000020c3a000 R11: 0000000000000246 R12: 00000000ffffffff
> R13: 00000000000006c0 R14: 00000000006e4760 R15: 00007f86cc483700


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