[....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.964766] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 14.604535] random: sshd: uninitialized urandom read (32 bytes read) [ 14.877940] random: sshd: uninitialized urandom read (32 bytes read) [ 15.747296] random: sshd: uninitialized urandom read (32 bytes read) [ 15.919042] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.30' (ECDSA) to the list of known hosts. [ 21.406571] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 21.492397] [ 21.494038] ====================================================== [ 21.500328] [ INFO: possible circular locking dependency detected ] [ 21.506704] 4.9.100-g73fdfa3 #26 Not tainted [ 21.511087] ------------------------------------------------------- [ 21.517465] syz-executor140/3570 is trying to acquire lock: [ 21.523157] (sk_lock-AF_INET){+.+.+.}, at: [] do_ip_setsockopt.isra.13+0x12a/0x2b10 [ 21.532972] but task is already holding lock: [ 21.537636] (rtnl_mutex){+.+.+.}, at: [] rtnl_lock+0x17/0x20 [ 21.545443] which lock already depends on the new lock. [ 21.545443] [ 21.552435] [ 21.552435] the existing dependency chain (in reverse order) is: [ 21.560026] -> #1 (rtnl_mutex){+.+.+.}: [ 21.564631] lock_acquire+0x130/0x3e0 [ 21.568923] mutex_lock_nested+0xc0/0x870 [ 21.573564] rtnl_lock+0x17/0x20 [ 21.577424] mrtsock_destruct+0x3b/0x1e0 [ 21.581979] ip_ra_control+0x2c2/0x420 [ 21.586354] do_ip_setsockopt.isra.13+0x15ff/0x2b10 [ 21.591865] ip_setsockopt+0x3a/0xb0 [ 21.596081] raw_setsockopt+0xb7/0xd0 [ 21.600384] sock_common_setsockopt+0x9a/0xe0 [ 21.605386] SyS_setsockopt+0x166/0x260 [ 21.609863] do_syscall_64+0x1a6/0x490 [ 21.614258] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 21.619866] -> #0 (sk_lock-AF_INET){+.+.+.}: [ 21.624946] __lock_acquire+0x3019/0x4070 [ 21.629599] lock_acquire+0x130/0x3e0 [ 21.633903] lock_sock_nested+0xc6/0x120 [ 21.638459] do_ip_setsockopt.isra.13+0x12a/0x2b10 [ 21.643877] ip_setsockopt+0x3a/0xb0 [ 21.648083] tcp_setsockopt+0x88/0xe0 [ 21.652375] sock_common_setsockopt+0x9a/0xe0 [ 21.657362] SyS_setsockopt+0x166/0x260 [ 21.661829] do_syscall_64+0x1a6/0x490 [ 21.666207] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 21.671805] [ 21.671805] other info that might help us debug this: [ 21.671805] [ 21.679917] Possible unsafe locking scenario: [ 21.679917] [ 21.685950] CPU0 CPU1 [ 21.690585] ---- ---- [ 21.695225] lock(rtnl_mutex); [ 21.698727] lock(sk_lock-AF_INET); [ 21.706130] lock(rtnl_mutex); [ 21.712140] lock(sk_lock-AF_INET); [ 21.716069] [ 21.716069] *** DEADLOCK *** [ 21.716069] [ 21.722116] 1 lock held by syz-executor140/3570: [ 21.726844] #0: (rtnl_mutex){+.+.+.}, at: [] rtnl_lock+0x17/0x20 [ 21.735175] [ 21.735175] stack backtrace: [ 21.739646] CPU: 1 PID: 3570 Comm: syz-executor140 Not tainted 4.9.100-g73fdfa3 #26 [ 21.747407] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 21.756732] ffff8801c84b7748 ffffffff81eb0f09 ffffffff855e7840 ffffffff8559d0e0 [ 21.764706] ffffffff855e7840 ffff8801c916a0e8 ffff8801c9169800 ffff8801c84b7790 [ 21.772708] ffffffff8142421d 0000000000000001 00000000c9169800 0000000000000001 [ 21.780683] Call Trace: [ 21.783251] [] dump_stack+0xc1/0x128 [ 21.788592] [] print_circular_bug.cold.51+0x1bd/0x27d [ 21.795407] [] __lock_acquire+0x3019/0x4070 [ 21.801350] [] ? debug_check_no_locks_freed+0x210/0x210 [ 21.808339] [] ? mark_held_locks+0xc7/0x130 [ 21.814296] [] ? mutex_lock_nested+0x572/0x870 [ 21.820501] [] lock_acquire+0x130/0x3e0 [ 21.826097] [] ? do_ip_setsockopt.isra.13+0x12a/0x2b10 [ 21.832998] [] lock_sock_nested+0xc6/0x120 [ 21.838859] [] ? do_ip_setsockopt.isra.13+0x12a/0x2b10 [ 21.845771] [] do_ip_setsockopt.isra.13+0x12a/0x2b10 [ 21.852507] [] ? get_empty_filp+0x11e/0x380 [ 21.858456] [] ? ip_ra_control+0x420/0x420 [ 21.864310] [] ? kmem_cache_alloc+0xbe/0x290 [ 21.870339] [] ? get_empty_filp+0x8f/0x380 [ 21.876194] [] ? alloc_file+0x20/0x350 [ 21.881704] [] ? sock_alloc_file+0x151/0x330 [ 21.887732] [] ? sock_map_fd+0x34/0x70 [ 21.893240] [] ? SyS_socket+0x10f/0x1b0 [ 21.898840] [] ? do_syscall_64+0x1a6/0x490 [ 21.904788] [] ? entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 21.911870] [] ? debug_check_no_locks_freed+0x210/0x210 [ 21.918864] [] ? debug_check_no_locks_freed+0x210/0x210 [ 21.925861] [] ? check_preemption_disabled+0x3b/0x170 [ 21.932682] [] ? sock_has_perm+0x1c2/0x3e0 [ 21.938547] [] ? sock_has_perm+0x292/0x3e0 [ 21.944408] [] ? sock_has_perm+0x9f/0x3e0 [ 21.950180] [] ? selinux_file_send_sigiotask+0x310/0x310 [ 21.957256] [] ? selinux_netlbl_socket_setsockopt+0x8c/0x340 [ 21.964676] [] ? selinux_netlbl_sock_rcv_skb+0x480/0x480 [ 21.971753] [] ip_setsockopt+0x3a/0xb0 [ 21.977268] [] tcp_setsockopt+0x88/0xe0 [ 21.982867] [] sock_common_setsockopt+0x9a/0xe0 [ 21.989165] [] SyS_setsockopt+0x166/0x260