Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.0.111' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 61.047298][ T6851] ------------[ cut here ]------------ [ 61.056794][ T6851] refcount_t: underflow; use-after-free. [ 61.064503][ T6851] WARNING: CPU: 1 PID: 6851 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 [ 61.076790][ T6851] Kernel panic - not syncing: panic_on_warn set ... [ 61.083390][ T6851] CPU: 1 PID: 6851 Comm: syz-executor133 Not tainted 5.9.0-rc2-syzkaller #0 [ 61.092054][ T6851] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 61.102110][ T6851] Call Trace: [ 61.105406][ T6851] dump_stack+0x18f/0x20d [ 61.109741][ T6851] panic+0x2e3/0x75c [ 61.113645][ T6851] ? __warn_printk+0xf3/0xf3 [ 61.118243][ T6851] ? __warn.cold+0x5/0x4a [ 61.122603][ T6851] ? __warn+0xd6/0x1f2 [ 61.126679][ T6851] ? refcount_warn_saturate+0x1d1/0x1e0 [ 61.132228][ T6851] __warn.cold+0x20/0x4a [ 61.136504][ T6851] ? refcount_warn_saturate+0x1d1/0x1e0 [ 61.142052][ T6851] report_bug+0x1bd/0x210 [ 61.146397][ T6851] handle_bug+0x38/0x90 [ 61.150552][ T6851] ? __warn_printk+0xc6/0xf3 [ 61.155143][ T6851] exc_invalid_op+0x14/0x40 [ 61.159647][ T6851] asm_exc_invalid_op+0x12/0x20 [ 61.164504][ T6851] RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 [ 61.170658][ T6851] Code: e9 db fe ff ff 48 89 df e8 dc ee 18 fe e9 8a fe ff ff e8 e2 d5 d8 fd 48 c7 c7 00 db 93 88 c6 05 da e4 11 07 01 e8 d1 e6 a9 fd <0f> 0b e9 af fe ff ff 0f 1f 84 00 00 00 00 00 41 56 41 55 41 54 55 [ 61.190261][ T6851] RSP: 0018:ffffc900016874a0 EFLAGS: 00010282 [ 61.196325][ T6851] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 61.204294][ T6851] RDX: ffff8880940580c0 RSI: ffffffff815dafc7 RDI: fffff520002d0e86 [ 61.212265][ T6851] RBP: 0000000000000003 R08: 0000000000000001 R09: ffff8880ae7318e7 [ 61.220235][ T6851] R10: 0000000000000000 R11: 0000000035383654 R12: ffff888099eec064 [ 61.228210][ T6851] R13: 00000000ffffffea R14: ffff888096264000 R15: ffff888099eec824 [ 61.236205][ T6851] ? vprintk_func+0x97/0x1a6 [ 61.240803][ T6851] qdisc_put+0xbe/0xe0 [ 61.244881][ T6851] ? red_offload.isra.0+0x480/0x480 [ 61.250078][ T6851] qdisc_create+0xcd9/0x12e0 [ 61.254676][ T6851] ? tc_get_qdisc+0xad0/0xad0 [ 61.259355][ T6851] ? lock_is_held_type+0xbb/0xf0 [ 61.264302][ T6851] tc_modify_qdisc+0x4c8/0x1990 [ 61.269162][ T6851] ? rtnetlink_rcv_msg+0x3f9/0xad0 [ 61.274278][ T6851] ? qdisc_create+0x12e0/0x12e0 [ 61.279146][ T6851] ? lock_is_held_type+0xbb/0xf0 [ 61.284096][ T6851] ? qdisc_create+0x12e0/0x12e0 [ 61.288946][ T6851] rtnetlink_rcv_msg+0x44e/0xad0 [ 61.293895][ T6851] ? rtnetlink_put_metrics+0x510/0x510 [ 61.299361][ T6851] ? lock_acquire+0x1f1/0xad0 [ 61.304047][ T6851] ? netlink_deliver_tap+0x146/0xb70 [ 61.309340][ T6851] netlink_rcv_skb+0x15a/0x430 [ 61.314105][ T6851] ? rtnetlink_put_metrics+0x510/0x510 [ 61.319654][ T6851] ? netlink_ack+0xa10/0xa10 [ 61.324543][ T6851] ? lock_is_held_type+0xbb/0xf0 [ 61.329509][ T6851] netlink_unicast+0x533/0x7d0 [ 61.334278][ T6851] ? netlink_attachskb+0x810/0x810 [ 61.339390][ T6851] ? _copy_from_iter_full+0x247/0x890 [ 61.344764][ T6851] ? __phys_addr+0x9a/0x110 [ 61.349266][ T6851] ? __phys_addr_symbol+0x2c/0x70 [ 61.354291][ T6851] ? __check_object_size+0x171/0x3e4 [ 61.359580][ T6851] netlink_sendmsg+0x856/0xd90 [ 61.364354][ T6851] ? netlink_unicast+0x7d0/0x7d0 [ 61.369305][ T6851] ? bpf_lsm_socket_sendmsg+0x5/0x10 [ 61.374590][ T6851] ? netlink_unicast+0x7d0/0x7d0 [ 61.379529][ T6851] sock_sendmsg+0xcf/0x120 [ 61.383948][ T6851] ____sys_sendmsg+0x6e8/0x810 [ 61.388715][ T6851] ? kernel_sendmsg+0x50/0x50 [ 61.393393][ T6851] ? do_recvmmsg+0x6d0/0x6d0 [ 61.397994][ T6851] ? mark_lock+0xbc/0x1710 [ 61.402415][ T6851] ? lock_is_held_type+0xbb/0xf0 [ 61.407357][ T6851] ? __lock_acquire+0xbb5/0x5640 [ 61.412384][ T6851] ___sys_sendmsg+0xf3/0x170 [ 61.416980][ T6851] ? sendmsg_copy_msghdr+0x160/0x160 [ 61.422274][ T6851] ? percpu_counter_add_batch+0x126/0x180 [ 61.428002][ T6851] ? lock_acquire+0x1f1/0xad0 [ 61.432683][ T6851] ? __get_unused_fd_flags+0x60/0x60 [ 61.437978][ T6851] ? find_held_lock+0x2d/0x110 [ 61.442807][ T6851] ? __fd_install+0x1b4/0x600 [ 61.447461][ T6851] ? lock_downgrade+0x830/0x830 [ 61.452302][ T6851] ? __fget_light+0x215/0x280 [ 61.456967][ T6851] __sys_sendmsg+0xe5/0x1b0 [ 61.461525][ T6851] ? __sys_sendmsg_sock+0xb0/0xb0 [ 61.466534][ T6851] ? trace_hardirqs_on+0x5f/0x220 [ 61.471538][ T6851] ? lockdep_hardirqs_on+0x76/0xf0 [ 61.476627][ T6851] do_syscall_64+0x2d/0x70 [ 61.481021][ T6851] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 61.487182][ T6851] RIP: 0033:0x4404a9 [ 61.491054][ T6851] Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 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 7b 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00 [ 61.510633][ T6851] RSP: 002b:00007ffc22b85dd8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e [ 61.519018][ T6851] RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004404a9 [ 61.526964][ T6851] RDX: 0000000000000000 RSI: 0000000020000240 RDI: 0000000000000004 [ 61.534914][ T6851] RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8 [ 61.542881][ T6851] R10: 00000000004002c8 R11: 0000000000000246 R12: 0000000000401cb0 [ 61.550828][ T6851] R13: 0000000000401d40 R14: 0000000000000000 R15: 0000000000000000 [ 61.559963][ T6851] Kernel Offset: disabled [ 61.564350][ T6851] Rebooting in 86400 seconds..