Warning: Permanently added '10.128.1.16' (ED25519) to the list of known hosts. 1970/01/01 00:00:30 parsed 1 programs syzkaller login: [ 31.851906][ T4339] cgroup: Unknown subsys name 'net' [ 32.125709][ T4339] cgroup: Unknown subsys name 'rlimit' Setting up swapspace version 1, size = 127995904 bytes [ 32.413543][ T4339] Adding 124996k swap on ./swap-file. Priority:0 extents:1 across:124996k SSFS [ 37.271487][ T4378] chnl_net:caif_netlink_parms(): no params data found [ 37.288404][ T4378] bridge0: port 1(bridge_slave_0) entered blocking state [ 37.289753][ T4378] bridge0: port 1(bridge_slave_0) entered disabled state [ 37.291513][ T4378] device bridge_slave_0 entered promiscuous mode [ 37.294203][ T4378] bridge0: port 2(bridge_slave_1) entered blocking state [ 37.295468][ T4378] bridge0: port 2(bridge_slave_1) entered disabled state [ 37.296957][ T4378] device bridge_slave_1 entered promiscuous mode [ 37.303714][ T4378] bond0: (slave bond_slave_0): Enslaving as an active interface with an up link [ 37.306729][ T4378] bond0: (slave bond_slave_1): Enslaving as an active interface with an up link [ 37.313040][ T4378] team0: Port device team_slave_0 added [ 37.316330][ T4378] team0: Port device team_slave_1 added [ 37.321397][ T4378] batman_adv: batadv0: Adding interface: batadv_slave_0 [ 37.322640][ T4378] batman_adv: batadv0: The MTU of interface batadv_slave_0 is too small (1500) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1560 would solve the problem. [ 37.327848][ T4378] batman_adv: batadv0: Not using interface batadv_slave_0 (retrying later): interface not active [ 37.330821][ T4378] batman_adv: batadv0: Adding interface: batadv_slave_1 [ 37.331867][ T4378] batman_adv: batadv0: The MTU of interface batadv_slave_1 is too small (1500) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1560 would solve the problem. [ 37.336480][ T4378] batman_adv: batadv0: Not using interface batadv_slave_1 (retrying later): interface not active [ 37.384236][ T4378] device hsr_slave_0 entered promiscuous mode [ 37.443217][ T4378] device hsr_slave_1 entered promiscuous mode [ 37.527875][ T4378] netdevsim netdevsim0 netdevsim0: renamed from eth0 [ 37.564795][ T4378] netdevsim netdevsim0 netdevsim1: renamed from eth1 [ 37.643651][ T4378] netdevsim netdevsim0 netdevsim2: renamed from eth2 [ 37.684833][ T4378] netdevsim netdevsim0 netdevsim3: renamed from eth3 [ 37.730718][ T4378] bridge0: port 2(bridge_slave_1) entered blocking state [ 37.732243][ T4378] bridge0: port 2(bridge_slave_1) entered forwarding state [ 37.733825][ T4378] bridge0: port 1(bridge_slave_0) entered blocking state [ 37.735216][ T4378] bridge0: port 1(bridge_slave_0) entered forwarding state [ 37.751646][ T4378] 8021q: adding VLAN 0 to HW filter on device bond0 [ 37.755972][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 37.758813][ T9] bridge0: port 1(bridge_slave_0) entered disabled state [ 37.760886][ T9] bridge0: port 2(bridge_slave_1) entered disabled state [ 37.767703][ T4378] 8021q: adding VLAN 0 to HW filter on device team0 [ 37.771144][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): bridge_slave_0: link becomes ready [ 37.773001][ T9] bridge0: port 1(bridge_slave_0) entered blocking state [ 37.774215][ T9] bridge0: port 1(bridge_slave_0) entered forwarding state [ 37.777628][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): bridge_slave_1: link becomes ready [ 37.779193][ T9] bridge0: port 2(bridge_slave_1) entered blocking state [ 37.780507][ T9] bridge0: port 2(bridge_slave_1) entered forwarding state [ 37.787014][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): team_slave_0: link becomes ready [ 37.788832][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): team0: link becomes ready [ 37.791886][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): team_slave_1: link becomes ready [ 37.796213][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_0: link becomes ready [ 37.799264][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready [ 37.802031][ T4378] IPv6: ADDRCONF(NETDEV_CHANGE): hsr0: link becomes ready [ 37.860804][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): vxcan0: link becomes ready [ 37.862340][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): vxcan1: link becomes ready [ 37.867643][ T4378] 8021q: adding VLAN 0 to HW filter on device batadv0 [ 37.873940][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_virt_wifi: link becomes ready [ 37.879754][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_vlan: link becomes ready [ 37.881631][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): vlan0: link becomes ready [ 37.883897][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): vlan1: link becomes ready [ 37.887988][ T4378] device veth0_vlan entered promiscuous mode [ 37.890945][ T4378] device veth1_vlan entered promiscuous mode [ 37.897611][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): macvlan0: link becomes ready [ 37.899258][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): macvlan1: link becomes ready [ 37.900936][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_macvtap: link becomes ready [ 37.903634][ T4378] device veth0_macvtap entered promiscuous mode [ 37.906055][ T4378] device veth1_macvtap entered promiscuous mode [ 37.911366][ T4378] batman_adv: batadv0: Interface activated: batadv_slave_0 [ 37.912822][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_batadv: link becomes ready [ 37.916749][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): macvtap0: link becomes ready [ 37.919655][ T4378] batman_adv: batadv0: Interface activated: batadv_slave_1 [ 37.921063][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready [ 37.924311][ T4378] netdevsim netdevsim0 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0 [ 37.926004][ T4378] netdevsim netdevsim0 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0 [ 37.927673][ T4378] netdevsim netdevsim0 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0 [ 37.929226][ T4378] netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0 [ 38.226306][ T4414] Bluetooth: hci0: unexpected cc 0x0c03 length: 249 > 1 [ 38.228043][ T4414] Bluetooth: hci0: unexpected cc 0x1003 length: 249 > 9 [ 38.229560][ T4414] Bluetooth: hci0: unexpected cc 0x1001 length: 249 > 9 [ 38.231591][ T4414] Bluetooth: hci0: unexpected cc 0x0c23 length: 249 > 4 [ 38.240580][ T4414] Bluetooth: hci0: unexpected cc 0x0c25 length: 249 > 3 [ 38.241954][ T4414] Bluetooth: hci0: unexpected cc 0x0c38 length: 249 > 2 [ 38.355176][ T39] wlan0: Created IBSS using preconfigured BSSID 50:50:50:50:50:50 [ 38.356693][ T39] wlan0: Creating new IBSS network, BSSID 50:50:50:50:50:50 [ 38.359116][ T39] IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready [ 38.372366][ T1711] wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50 [ 38.373987][ T1711] wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50 [ 38.375900][ T1711] IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready 1970/01/01 00:00:38 executed programs: 0 [ 38.919216][ T47] Bluetooth: hci0: unexpected cc 0x0c03 length: 249 > 1 [ 38.920959][ T47] Bluetooth: hci0: unexpected cc 0x1003 length: 249 > 9 [ 38.922413][ T47] Bluetooth: hci0: unexpected cc 0x1001 length: 249 > 9 [ 38.924387][ T47] Bluetooth: hci0: unexpected cc 0x0c23 length: 249 > 4 [ 38.926100][ T47] Bluetooth: hci0: unexpected cc 0x0c25 length: 249 > 3 [ 38.927442][ T47] Bluetooth: hci0: unexpected cc 0x0c38 length: 249 > 2 [ 39.166108][ T58] netdevsim netdevsim0 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 [ 39.204726][ T4438] chnl_net:caif_netlink_parms(): no params data found [ 39.221967][ T4438] bridge0: port 1(bridge_slave_0) entered blocking state [ 39.223532][ T4438] bridge0: port 1(bridge_slave_0) entered disabled state [ 39.225209][ T4438] device bridge_slave_0 entered promiscuous mode [ 39.227297][ T4438] bridge0: port 2(bridge_slave_1) entered blocking state [ 39.228618][ T4438] bridge0: port 2(bridge_slave_1) entered disabled state [ 39.230219][ T4438] device bridge_slave_1 entered promiscuous mode [ 39.239036][ T4438] bond0: (slave bond_slave_0): Enslaving as an active interface with an up link [ 39.241819][ T4438] bond0: (slave bond_slave_1): Enslaving as an active interface with an up link [ 39.248847][ T4438] team0: Port device team_slave_0 added [ 39.250631][ T4438] team0: Port device team_slave_1 added [ 39.259304][ T4438] batman_adv: batadv0: Adding interface: batadv_slave_0 [ 39.260571][ T4438] batman_adv: batadv0: The MTU of interface batadv_slave_0 is too small (1500) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1560 would solve the problem. [ 39.265510][ T4438] batman_adv: batadv0: Not using interface batadv_slave_0 (retrying later): interface not active [ 39.267980][ T4438] batman_adv: batadv0: Adding interface: batadv_slave_1 [ 39.269180][ T4438] batman_adv: batadv0: The MTU of interface batadv_slave_1 is too small (1500) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1560 would solve the problem. [ 39.273708][ T4438] batman_adv: batadv0: Not using interface batadv_slave_1 (retrying later): interface not active [ 39.294305][ T4438] device hsr_slave_0 entered promiscuous mode [ 39.333272][ T4438] device hsr_slave_1 entered promiscuous mode [ 39.373085][ T4438] debugfs: Directory 'hsr0' with parent 'hsr' already present! [ 39.374617][ T4438] Cannot create hsr debugfs directory [ 40.983478][ T4414] Bluetooth: hci0: command 0x0409 tx timeout [ 41.114179][ T58] netdevsim netdevsim0 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 [ 43.063400][ T4414] Bluetooth: hci0: command 0x041b tx timeout [ 43.514190][ T58] netdevsim netdevsim0 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 [ 43.594815][ T58] netdevsim netdevsim0 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 [ 44.476660][ T4438] netdevsim netdevsim0 netdevsim0: renamed from eth0 [ 44.565323][ T4438] netdevsim netdevsim0 netdevsim1: renamed from eth1 [ 44.666646][ T4438] netdevsim netdevsim0 netdevsim2: renamed from eth2 [ 44.755177][ T4438] netdevsim netdevsim0 netdevsim3: renamed from eth3 [ 44.814719][ T4438] 8021q: adding VLAN 0 to HW filter on device bond0 [ 44.907798][ T39] IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready [ 44.909584][ T39] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 44.912104][ T4438] 8021q: adding VLAN 0 to HW filter on device team0 [ 44.914735][ T39] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 44.916542][ T39] IPv6: ADDRCONF(NETDEV_CHANGE): bridge_slave_0: link becomes ready [ 44.918076][ T39] bridge0: port 1(bridge_slave_0) entered blocking state [ 44.919389][ T39] bridge0: port 1(bridge_slave_0) entered forwarding state [ 44.920997][ T39] IPv6: ADDRCONF(NETDEV_CHANGE): bridge0: link becomes ready [ 44.924392][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 44.926187][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): bridge_slave_1: link becomes ready [ 44.927763][ T9] bridge0: port 2(bridge_slave_1) entered blocking state [ 44.929062][ T9] bridge0: port 2(bridge_slave_1) entered forwarding state [ 44.931900][ T39] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bond: link becomes ready [ 44.965791][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bond: link becomes ready [ 44.968804][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_team: link becomes ready [ 44.970994][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): team_slave_0: link becomes ready [ 44.972676][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): team0: link becomes ready [ 44.975758][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_team: link becomes ready [ 44.977507][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): team_slave_1: link becomes ready [ 44.980934][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_hsr: link becomes ready [ 44.982554][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_0: link becomes ready [ 44.985482][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_hsr: link becomes ready [ 44.987086][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready [ 44.989526][ T4438] IPv6: ADDRCONF(NETDEV_CHANGE): hsr0: link becomes ready [ 45.089226][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): vxcan1: link becomes ready [ 45.090700][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): vxcan0: link becomes ready [ 45.094707][ T4438] 8021q: adding VLAN 0 to HW filter on device batadv0 [ 45.100118][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_virt_wifi: link becomes ready [ 45.101841][ T9] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_virt_wifi: link becomes ready [ 45.108194][ T1711] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_vlan: link becomes ready [ 45.109629][ T1711] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_vlan: link becomes ready [ 45.111281][ T1711] IPv6: ADDRCONF(NETDEV_CHANGE): vlan0: link becomes ready [ 45.112890][ T1711] IPv6: ADDRCONF(NETDEV_CHANGE): vlan1: link becomes ready [ 45.133107][ T4414] Bluetooth: hci0: command 0x040f tx timeout [ 45.166669][ T4438] device veth0_vlan entered promiscuous mode [ 45.170435][ T4438] device veth1_vlan entered promiscuous mode [ 45.177194][ T1711] IPv6: ADDRCONF(NETDEV_CHANGE): macvlan0: link becomes ready [ 45.178902][ T1711] IPv6: ADDRCONF(NETDEV_CHANGE): macvlan1: link becomes ready [ 45.180487][ T1711] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_macvtap: link becomes ready [ 45.182194][ T1711] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_macvtap: link becomes ready [ 45.187387][ T4438] device veth0_macvtap entered promiscuous mode [ 45.189825][ T4438] device veth1_macvtap entered promiscuous mode [ 45.195232][ T4438] batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_0 [ 45.197165][ T4438] batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! [ 45.199353][ T4438] batman_adv: batadv0: Interface activated: batadv_slave_0 [ 45.200648][ T1711] IPv6: ADDRCONF(NETDEV_CHANGE): macvtap0: link becomes ready [ 45.202289][ T1711] IPv6: ADDRCONF(NETDEV_CHANGE): macsec0: link becomes ready [ 45.205091][ T1711] IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_0: link becomes ready [ 45.206752][ T1711] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_batadv: link becomes ready [ 45.209227][ T4438] batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3f) already exists on: batadv_slave_1 [ 45.211081][ T4438] batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! [ 45.213914][ T4438] batman_adv: batadv0: Interface activated: batadv_slave_1 [ 45.215257][ T1711] IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready [ 45.217096][ T1711] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready [ 45.219607][ T4438] netdevsim netdevsim0 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0 [ 45.221242][ T4438] netdevsim netdevsim0 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0 [ 45.222799][ T4438] netdevsim netdevsim0 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0 [ 45.225306][ T4438] netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0 [ 45.301283][ T1711] wlan0: Created IBSS using preconfigured BSSID 50:50:50:50:50:50 [ 45.304330][ T1711] wlan0: Creating new IBSS network, BSSID 50:50:50:50:50:50 [ 45.306212][ T39] IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready [ 45.312121][ T39] wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50 [ 45.314119][ T39] wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50 [ 45.315484][ T1711] IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready [ 45.474526][ T4537] netlink: 44 bytes leftover after parsing attributes in process `syz.0.17'. [ 45.476185][ T4537] ------------[ cut here ]------------ [ 45.477185][ T4537] memcpy: detected field-spanning write (size 32) of single field "&new->sel" at net/sched/cls_u32.c:853 (size 16) [ 45.479734][ T4537] WARNING: CPU: 1 PID: 4537 at net/sched/cls_u32.c:853 u32_change+0x1698/0x1f18 [ 45.481270][ T4537] Modules linked in: [ 45.481900][ T4537] CPU: 1 PID: 4537 Comm: syz.0.17 Not tainted syzkaller #0 [ 45.483196][ T4537] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 [ 45.485066][ T4537] pstate: 62400005 (nZCv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--) [ 45.486465][ T4537] pc : u32_change+0x1698/0x1f18 [ 45.487366][ T4537] lr : u32_change+0x1698/0x1f18 [ 45.488281][ T4537] sp : ffff800021646be0 [ 45.489073][ T4537] x29: ffff800021646d40 x28: ffff0000d4b8c000 x27: 0000000000000000 [ 45.490598][ T4537] x26: 1fffe0001a97180d x25: ffff0000d4b98400 x24: ffff0000d4b8c400 [ 45.492116][ T4537] x23: 0000000000000010 x22: ffff7000042c8d8c x21: dfff800000000000 [ 45.493547][ T4537] x20: ffff800021647400 x19: ffff800017c11000 x18: ffff800011babf60 [ 45.495093][ T4537] x17: 20646c6569662065 x16: ffff800011a529a8 x15: 0000000000000000 [ 45.496622][ T4537] x14: 0000000000000001 x13: 1fffe00033ea39a3 x12: 0000000000ff0100 [ 45.498190][ T4537] x11: ff00800008194b40 x10: 0000000000000000 x9 : 836b2d3191fa7400 [ 45.499739][ T4537] x8 : 836b2d3191fa7400 x7 : 0000000000000001 x6 : 0000000000000001 [ 45.501365][ T4537] x5 : ffff800021646678 x4 : ffff800015324ea0 x3 : ffff80000853974c [ 45.502931][ T4537] x2 : 0000000000000001 x1 : 0000000100000000 x0 : 0000000000000000 [ 45.504430][ T4537] Call trace: [ 45.505037][ T4537] u32_change+0x1698/0x1f18 [ 45.505847][ T4537] tc_new_tfilter+0xf60/0x1474 [ 45.506716][ T4537] rtnetlink_rcv_msg+0x6d8/0xcdc [ 45.507654][ T4537] netlink_rcv_skb+0x218/0x3e8 [ 45.508525][ T4537] rtnetlink_rcv+0x28/0x38 [ 45.509382][ T4537] netlink_unicast+0x60c/0x814 [ 45.510260][ T4537] netlink_sendmsg+0x6f4/0x9c0 [ 45.511183][ T4537] ____sys_sendmsg+0x5c8/0x938 [ 45.512084][ T4537] __sys_sendmmsg+0x344/0x834 [ 45.513030][ T4537] __arm64_sys_sendmmsg+0xa0/0xbc [ 45.514000][ T4537] invoke_syscall+0x98/0x290 [ 45.514837][ T4537] el0_svc_common+0x138/0x258 [ 45.515709][ T4537] do_el0_svc+0x58/0x130 [ 45.516515][ T4537] el0_svc+0x58/0x128 [ 45.517270][ T4537] el0t_64_sync_handler+0x84/0xf0 [ 45.518177][ T4537] el0t_64_sync+0x18c/0x190 [ 45.519016][ T4537] irq event stamp: 2184 [ 45.519827][ T4537] hardirqs last enabled at (2183): [] __up_console_sem+0xb4/0xfc [ 45.521620][ T4537] hardirqs last disabled at (2184): [] el1_dbg+0x24/0x80 [ 45.523279][ T4537] softirqs last enabled at (2178): [] handle_softirqs+0xaec/0xc60 [ 45.525119][ T4537] softirqs last disabled at (2067): [] __do_softirq+0x14/0x20 [ 45.526806][ T4537] ---[ end trace 0000000000000000 ]--- [ 45.528393][ T4537] Zero length message leads to an empty skb