bpfilter: read fail -512 ============================= WARNING: suspicious RCU usage 4.19.0-rc4+ #27 Not tainted ----------------------------- kernel/pid.c:330 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-executor3/29639: #0: 00000000d4e7c879 (bpfilter_lock){+.+.}, at: __bpfilter_process_sockopt+0x1d0/0x387 net/bpfilter/bpfilter_kern.c:64 stack backtrace: CPU: 1 PID: 29639 Comm: syz-executor3 Not tainted 4.19.0-rc4+ #27 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+0x1c4/0x2b4 lib/dump_stack.c:113 lockdep_rcu_suspicious+0x14a/0x153 kernel/locking/lockdep.c:4536 pid_task+0x1ce/0x200 kernel/pid.c:329 shutdown_umh.constprop.0+0x33/0x7c net/bpfilter/bpfilter_kern.c:26 __stop_umh net/bpfilter/bpfilter_kern.c:38 [inline] __bpfilter_process_sockopt.cold.1+0x9b/0xa0 net/bpfilter/bpfilter_kern.c:78 bpfilter_mbox_request+0x4d/0xb0 net/ipv4/bpfilter/sockopt.c:25 bpfilter_ip_get_sockopt+0x6b/0x90 net/ipv4/bpfilter/sockopt.c:42 ip_getsockopt+0x23c/0x2a0 net/ipv4/ip_sockglue.c:1566 tcp_getsockopt+0x93/0xe0 net/ipv4/tcp.c:3583 sock_common_getsockopt+0x9a/0xe0 net/core/sock.c:2997 __sys_getsockopt+0x1ad/0x390 net/socket.c:1939 __do_sys_getsockopt net/socket.c:1950 [inline] __se_sys_getsockopt net/socket.c:1947 [inline] __x64_sys_getsockopt+0xbe/0x150 net/socket.c:1947 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457679 Code: 1d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fe28247ec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037 RAX: ffffffffffffffda RBX: 00007fe28247f6d4 RCX: 0000000000457679 RDX: 0000000000000042 RSI: 0000000000000000 RDI: 0000000000000004 RBP: 000000000072c040 R08: 0000000020000080 R09: 0000000000000000 R10: 0000000020000040 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000004cd1b0 R14: 00000000004c7078 R15: 0000000000000002