Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.0.113' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 60.173559][ T6846] ------------[ cut here ]------------ [ 60.188289][ T6846] refcount_t: underflow; use-after-free. [ 60.194433][ T6846] WARNING: CPU: 0 PID: 6846 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 [ 60.251595][ T6846] Kernel panic - not syncing: panic_on_warn set ... [ 60.258224][ T6846] CPU: 0 PID: 6846 Comm: syz-executor093 Not tainted 5.9.0-rc1-syzkaller #0 [ 60.266892][ T6846] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 60.276947][ T6846] Call Trace: [ 60.280244][ T6846] dump_stack+0x18f/0x20d [ 60.284582][ T6846] panic+0x2e3/0x75c [ 60.288480][ T6846] ? __warn_printk+0xf3/0xf3 [ 60.293079][ T6846] ? console_unlock+0x7f0/0xf30 [ 60.297934][ T6846] ? __warn.cold+0x5/0x4a [ 60.302271][ T6846] ? __warn+0xd6/0x1f2 [ 60.306342][ T6846] ? refcount_warn_saturate+0x1d1/0x1e0 [ 60.311894][ T6846] __warn.cold+0x20/0x4a [ 60.316144][ T6846] ? refcount_warn_saturate+0x1d1/0x1e0 [ 60.321695][ T6846] report_bug+0x1bd/0x210 [ 60.326035][ T6846] handle_bug+0x38/0x90 [ 60.330193][ T6846] ? __warn_printk+0xc6/0xf3 [ 60.334786][ T6846] exc_invalid_op+0x14/0x40 [ 60.339481][ T6846] asm_exc_invalid_op+0x12/0x20 [ 60.344335][ T6846] RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 [ 60.350492][ T6846] Code: e9 db fe ff ff 48 89 df e8 8c f3 18 fe e9 8a fe ff ff e8 92 da d8 fd 48 c7 c7 00 db 93 88 c6 05 ca e9 11 07 01 e8 81 eb a9 fd <0f> 0b e9 af fe ff ff 0f 1f 84 00 00 00 00 00 41 56 41 55 41 54 55 [ 60.370208][ T6846] RSP: 0018:ffffc900020074a0 EFLAGS: 00010282 [ 60.376277][ T6846] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 60.384399][ T6846] RDX: ffff888098030380 RSI: ffffffff815dafc7 RDI: fffff52000400e86 [ 60.392376][ T6846] RBP: 0000000000000003 R08: 0000000000000001 R09: ffff8880ae620f8b [ 60.400351][ T6846] R10: 0000000000000000 R11: 0000000034383654 R12: ffff88809a892864 [ 60.408353][ T6846] R13: 00000000ffffffea R14: ffff88809e842000 R15: ffff888099cc0024 [ 60.416346][ T6846] ? vprintk_func+0x97/0x1a6 [ 60.420949][ T6846] qdisc_put+0xbe/0xe0 [ 60.425023][ T6846] ? red_offload.isra.0+0x480/0x480 [ 60.430227][ T6846] qdisc_create+0xcd9/0x12e0 [ 60.434826][ T6846] ? tc_get_qdisc+0xad0/0xad0 [ 60.439513][ T6846] ? lock_is_held_type+0xbb/0xf0 [ 60.444468][ T6846] tc_modify_qdisc+0x4c8/0x1990 [ 60.449337][ T6846] ? rtnetlink_rcv_msg+0x3f9/0xad0 [ 60.454457][ T6846] ? qdisc_create+0x12e0/0x12e0 [ 60.459331][ T6846] ? lock_is_held_type+0xbb/0xf0 [ 60.464270][ T6846] ? qdisc_create+0x12e0/0x12e0 [ 60.469118][ T6846] rtnetlink_rcv_msg+0x44e/0xad0 [ 60.474060][ T6846] ? rtnetlink_put_metrics+0x510/0x510 [ 60.479521][ T6846] ? lock_acquire+0x1f1/0xad0 [ 60.484200][ T6846] ? netlink_deliver_tap+0x146/0xb70 [ 60.489491][ T6846] netlink_rcv_skb+0x15a/0x430 [ 60.494257][ T6846] ? rtnetlink_put_metrics+0x510/0x510 [ 60.499712][ T6846] ? netlink_ack+0xa10/0xa10 [ 60.504285][ T6846] ? lock_is_held_type+0xbb/0xf0 [ 60.509201][ T6846] netlink_unicast+0x533/0x7d0 [ 60.513945][ T6846] ? netlink_attachskb+0x810/0x810 [ 60.519033][ T6846] ? _copy_from_iter_full+0x247/0x890 [ 60.524378][ T6846] ? __phys_addr+0x9a/0x110 [ 60.528862][ T6846] ? __phys_addr_symbol+0x2c/0x70 [ 60.533861][ T6846] ? __check_object_size+0x171/0x3e4 [ 60.539121][ T6846] netlink_sendmsg+0x856/0xd90 [ 60.543862][ T6846] ? netlink_unicast+0x7d0/0x7d0 [ 60.548778][ T6846] ? bpf_lsm_socket_sendmsg+0x5/0x10 [ 60.554035][ T6846] ? netlink_unicast+0x7d0/0x7d0 [ 60.558949][ T6846] sock_sendmsg+0xcf/0x120 [ 60.563340][ T6846] ____sys_sendmsg+0x6e8/0x810 [ 60.568092][ T6846] ? kernel_sendmsg+0x50/0x50 [ 60.572746][ T6846] ? do_recvmmsg+0x6d0/0x6d0 [ 60.577310][ T6846] ? mark_lock+0xbc/0x1710 [ 60.581750][ T6846] ? lock_is_held_type+0xbb/0xf0 [ 60.586663][ T6846] ? __lock_acquire+0xbb5/0x5640 [ 60.591576][ T6846] ___sys_sendmsg+0xf3/0x170 [ 60.596145][ T6846] ? sendmsg_copy_msghdr+0x160/0x160 [ 60.601412][ T6846] ? percpu_counter_add_batch+0x126/0x180 [ 60.607109][ T6846] ? lock_acquire+0x1f1/0xad0 [ 60.611759][ T6846] ? __get_unused_fd_flags+0x60/0x60 [ 60.617052][ T6846] ? find_held_lock+0x2d/0x110 [ 60.621800][ T6846] ? __fd_install+0x1b4/0x600 [ 60.626457][ T6846] ? lock_downgrade+0x830/0x830 [ 60.631283][ T6846] ? __fget_light+0x215/0x280 [ 60.635935][ T6846] __sys_sendmsg+0xe5/0x1b0 [ 60.640412][ T6846] ? __sys_sendmsg_sock+0xb0/0xb0 [ 60.645415][ T6846] ? trace_hardirqs_on+0x5f/0x220 [ 60.650416][ T6846] ? lockdep_hardirqs_on+0x76/0xf0 [ 60.655500][ T6846] do_syscall_64+0x2d/0x70 [ 60.659892][ T6846] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 60.665757][ T6846] RIP: 0033:0x4404a9 [ 60.669630][ T6846] 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 [ 60.689208][ T6846] RSP: 002b:00007ffd48790178 EFLAGS: 00000246 ORIG_RAX: 000000000000002e [ 60.697593][ T6846] RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004404a9 [ 60.705572][ T6846] RDX: 0000000000000000 RSI: 0000000020000240 RDI: 0000000000000004 [ 60.713552][ T6846] RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8 [ 60.721499][ T6846] R10: 00000000004002c8 R11: 0000000000000246 R12: 0000000000401cb0 [ 60.729447][ T6846] R13: 0000000000401d40 R14: 0000000000000000 R15: 0000000000000000 [ 60.738799][ T6846] Kernel Offset: disabled [ 60.743190][ T6846] Rebooting in 86400 seconds..