==================================================================
BUG: KASAN: slab-out-of-bounds in smc_fback_state_change+0x78/0xac net/smc/af_smc.c:834
Read of size 8 at addr ffff0000f6d92524 by task syz.4.464/6273

CPU: 1 PID: 6273 Comm: syz.4.464 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2026
Call trace:
 dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106
 print_address_description+0x88/0x218 mm/kasan/report.c:316
 print_report+0x50/0x68 mm/kasan/report.c:420
 kasan_report+0xa8/0xfc mm/kasan/report.c:524
 __asan_report_load8_noabort+0x2c/0x38 mm/kasan/report_generic.c:351
 smc_fback_state_change+0x78/0xac net/smc/af_smc.c:834
 tcp_rcv_state_process+0x1d38/0x37c0 net/ipv4/tcp_input.c:6670
 tcp_child_process+0x2e8/0x934 net/ipv4/tcp_minisocks.c:858
 tcp_v4_rcv+0x1bb4/0x24d0 net/ipv4/tcp_ipv4.c:2073
 ip_protocol_deliver_rcu+0x34c/0x780 net/ipv4/ip_input.c:205
 ip_local_deliver_finish+0x250/0x484 net/ipv4/ip_input.c:233
 NF_HOOK+0x2dc/0x36c include/linux/netfilter.h:302
 ip_local_deliver+0x120/0x190 net/ipv4/ip_input.c:254
 dst_input include/net/dst.h:463 [inline]
 ip_rcv_finish+0x220/0x24c net/ipv4/ip_input.c:449
 NF_HOOK+0x2dc/0x36c include/linux/netfilter.h:302
 ip_rcv+0x7c/0x9c net/ipv4/ip_input.c:569
 __netif_receive_skb_one_core net/core/dev.c:5619 [inline]
 __netif_receive_skb+0xd0/0x2b0 net/core/dev.c:5733
 process_backlog+0x42c/0x748 net/core/dev.c:6061
 __napi_poll+0xb8/0x3f4 net/core/dev.c:6628
 napi_poll net/core/dev.c:6695 [inline]
 net_rx_action+0x52c/0xb5c net/core/dev.c:6809
 handle_softirqs+0x318/0xc90 kernel/softirq.c:596
 __do_softirq+0x14/0x20 kernel/softirq.c:630
 ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:80
 call_on_irq_stack+0x30/0x48 arch/arm64/kernel/entry.S:897
 do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:85
 do_softirq+0xf8/0x1a0 kernel/softirq.c:497
 __local_bh_enable_ip+0x250/0x37c kernel/softirq.c:421
 local_bh_enable+0x28/0x34 include/linux/bottom_half.h:33
 rcu_read_unlock_bh include/linux/rcupdate.h:861 [inline]
 __dev_queue_xmit+0x16f8/0x3154 net/core/dev.c:4411
 dev_queue_xmit include/linux/netdevice.h:3053 [inline]
 neigh_hh_output include/net/neighbour.h:533 [inline]
 neigh_output include/net/neighbour.h:547 [inline]
 ip_finish_output2+0xc08/0x10a8 net/ipv4/ip_output.c:228
 __ip_finish_output+0x1b0/0x448 net/ipv4/ip_output.c:-1
 ip_finish_output+0x40/0x264 net/ipv4/ip_output.c:316
 NF_HOOK_COND include/linux/netfilter.h:291 [inline]
 ip_output+0x3b4/0x554 net/ipv4/ip_output.c:434
 dst_output include/net/dst.h:453 [inline]
 ip_local_out net/ipv4/ip_output.c:126 [inline]
 __ip_queue_xmit+0xcbc/0x1718 net/ipv4/ip_output.c:538
 ip_queue_xmit+0x5c/0x7c net/ipv4/ip_output.c:552
 __tcp_transmit_skb+0x17bc/0x2bcc net/ipv4/tcp_output.c:1407
 __tcp_send_ack+0x240/0x4e8 net/ipv4/tcp_output.c:4061
 tcp_send_ack+0x4c/0x68 net/ipv4/tcp_output.c:4067
 tcp_rcv_synsent_state_process net/ipv4/tcp_input.c:6423 [inline]
 tcp_rcv_state_process+0x2354/0x37c0 net/ipv4/tcp_input.c:6600
 tcp_v4_do_rcv+0x670/0xa68 net/ipv4/tcp_ipv4.c:1715
 sk_backlog_rcv include/net/sock.h:1138 [inline]
 __release_sock+0x1b0/0x3b0 net/core/sock.c:2953
 release_sock+0x60/0x1bc net/core/sock.c:3519
 inet_wait_for_connect net/ipv4/af_inet.c:600 [inline]
 __inet_stream_connect+0x6b4/0xc48 net/ipv4/af_inet.c:694
 inet_stream_connect+0x74/0xb0 net/ipv4/af_inet.c:739
 kernel_connect+0x124/0x190 net/socket.c:3555
 smc_connect+0x5ac/0xadc net/smc/af_smc.c:1655
 __sys_connect_file net/socket.c:2011 [inline]
 __sys_connect+0x28c/0x2b4 net/socket.c:2028
 __do_sys_connect net/socket.c:2038 [inline]
 __se_sys_connect net/socket.c:2035 [inline]
 __arm64_sys_connect+0x7c/0x94 net/socket.c:2035
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

Allocated by task 6273:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4c/0x80 mm/kasan/common.c:53
 kasan_save_alloc_info+0x24/0x30 mm/kasan/generic.c:505
 ____kasan_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0xa0/0xb8 mm/kasan/common.c:384
 kasan_kmalloc include/linux/kasan.h:211 [inline]
 kmalloc_node_trace+0x78/0x90 mm/slab_common.c:1043
 kmalloc_node include/linux/slab.h:585 [inline]
 kzalloc_node include/linux/slab.h:710 [inline]
 sk_psock_init+0xf8/0x634 net/core/skmsg.c:765
 sock_map_link+0x5e0/0xaf4 net/core/sock_map.c:278
 sock_hash_update_common+0xdc/0x948 net/core/sock_map.c:999
 ____bpf_sock_hash_update net/core/sock_map.c:1227 [inline]
 bpf_sock_hash_update+0x10c/0x164 net/core/sock_map.c:1220
 bpf_prog_ea9d1f3f5bfee3af+0x78/0xb0
 bpf_dispatcher_nop_func include/linux/bpf.h:1012 [inline]
 __bpf_prog_run include/linux/filter.h:608 [inline]
 bpf_prog_run include/linux/filter.h:615 [inline]
 bpf_prog_run_array_cg kernel/bpf/cgroup.c:68 [inline]
 __cgroup_bpf_run_filter_sock_ops+0x26c/0x5d0 kernel/bpf/cgroup.c:1532
 bpf_skops_established net/ipv4/tcp_input.c:192 [inline]
 tcp_init_transfer+0xfc8/0x102c net/ipv4/tcp_input.c:6153
 tcp_rcv_state_process+0x1cdc/0x37c0 net/ipv4/tcp_input.c:6664
 tcp_child_process+0x2e8/0x934 net/ipv4/tcp_minisocks.c:858
 tcp_v4_rcv+0x1bb4/0x24d0 net/ipv4/tcp_ipv4.c:2073
 ip_protocol_deliver_rcu+0x34c/0x780 net/ipv4/ip_input.c:205
 ip_local_deliver_finish+0x250/0x484 net/ipv4/ip_input.c:233
 NF_HOOK+0x2dc/0x36c include/linux/netfilter.h:302
 ip_local_deliver+0x120/0x190 net/ipv4/ip_input.c:254
 dst_input include/net/dst.h:463 [inline]
 ip_rcv_finish+0x220/0x24c net/ipv4/ip_input.c:449
 NF_HOOK+0x2dc/0x36c include/linux/netfilter.h:302
 ip_rcv+0x7c/0x9c net/ipv4/ip_input.c:569
 __netif_receive_skb_one_core net/core/dev.c:5619 [inline]
 __netif_receive_skb+0xd0/0x2b0 net/core/dev.c:5733
 process_backlog+0x42c/0x748 net/core/dev.c:6061
 __napi_poll+0xb8/0x3f4 net/core/dev.c:6628
 napi_poll net/core/dev.c:6695 [inline]
 net_rx_action+0x52c/0xb5c net/core/dev.c:6809
 handle_softirqs+0x318/0xc90 kernel/softirq.c:596
 __do_softirq+0x14/0x20 kernel/softirq.c:630

Last potentially related work creation:
 kasan_save_stack+0x40/0x70 mm/kasan/common.c:46
 __kasan_record_aux_stack+0xc0/0xdc mm/kasan/generic.c:486
 kasan_record_aux_stack_noalloc+0x14/0x20 mm/kasan/generic.c:496
 kvfree_call_rcu+0xb4/0x6f0 kernel/rcu/tree.c:3405
 neigh_destroy+0x460/0x658 net/core/neighbour.c:923
 neigh_release include/net/neighbour.h:448 [inline]
 neigh_cleanup_and_release+0x154/0x3b4 net/core/neighbour.c:104
 neigh_flush_dev+0x1a4/0x7f8 net/core/neighbour.c:430
 __neigh_ifdown+0x54/0x3d8 net/core/neighbour.c:447
 neigh_ifdown+0x2c/0x40 net/core/neighbour.c:465
 rt6_disable_ip+0x758/0x7c4 net/ipv6/route.c:4953
 addrconf_ifdown+0x150/0x1630 net/ipv6/addrconf.c:3805
 addrconf_notify+0x344/0xc98 net/ipv6/addrconf.c:-1
 notifier_call_chain kernel/notifier.c:87 [inline]
 raw_notifier_call_chain+0xd8/0x168 kernel/notifier.c:455
 call_netdevice_notifiers_info net/core/dev.c:2014 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:2052 [inline]
 call_netdevice_notifiers net/core/dev.c:2066 [inline]
 dev_close_many+0x2d4/0x448 net/core/dev.c:1614
 unregister_netdevice_many_notify+0x3f4/0x1900 net/core/dev.c:10997
 unregister_netdevice_many net/core/dev.c:11077 [inline]
 default_device_exit_batch+0x9d4/0xa70 net/core/dev.c:11549
 ops_exit_list net/core/net_namespace.c:177 [inline]
 cleanup_net+0x650/0xa90 net/core/net_namespace.c:640
 process_one_work+0x7e4/0x13bc kernel/workqueue.c:2292
 worker_thread+0x8cc/0xfe8 kernel/workqueue.c:2439
 kthread+0x254/0x2e0 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:850

The buggy address belongs to the object at ffff0000f6d92000
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 292 bytes to the right of
 1024-byte region [ffff0000f6d92000, ffff0000f6d92400)

The buggy address belongs to the physical page:
page:00000000f7f1ebcc refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x136d90
head:00000000f7f1ebcc order:3 compound_mapcount:0 compound_pincount:0
flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000010200 0000000000000000 dead000000000001 ffff0000c0002780
raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000f6d92400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff0000f6d92480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff0000f6d92500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                               ^
 ffff0000f6d92580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff0000f6d92600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
Mem abort info:
  ESR = 0x0000000086000006
  EC = 0x21: IABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x06: level 2 translation fault
user pgtable: 4k pages, 48-bit VAs, pgdp=000000014e450000
[0000000000000000] pgd=080000011f442003, p4d=080000011f442003, pud=0800000134e75003, pmd=0000000000000000
Internal error: Oops: 0000000086000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 6261 Comm: syz.4.464 Tainted: G    B              syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2026
pstate: 02400805 (nzcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=-c)
pc : 0x0
lr : smc_fback_forward_wakeup+0x1cc/0x4d0 net/smc/af_smc.c:817
sp : ffff8000080171a0
x29: ffff800008017250 x28: ffff0000e1b53040 x27: 1fffe0001a176e11
x26: ffff8000080171a0 x25: dfff800000000000 x24: ffff700001002e34
x23: 0000000000000000 x22: ffff0000d0bb7088 x21: ffff0000d0bb6e40
x20: 0000000000000000 x19: ffff0000f6d92004 x18: 0000000000000000
x17: ffff80018a057000 x16: ffff800008043b30 x15: 0000000000000000
x14: 0000000000000001 x13: 1fffe0001c36a608 x12: 0000000000000000
x11: ff00800008048e14 x10: 0000000000000304 x9 : dfff800000000000
x8 : 0000000100000303 x7 : 0000000000000000 x6 : ffff8000082b6150
x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000000
x2 : ffff800008017060 x1 : 0000000000000000 x0 : ffff0000d0bb6e40
Call trace:
 0x0
 smc_fback_state_change+0x88/0xac net/smc/af_smc.c:833
 tcp_fin+0x22c/0x3dc net/ipv4/tcp_input.c:4516
 tcp_data_queue+0xb08/0x4e48 net/ipv4/tcp_input.c:5161
 tcp_rcv_established+0xcd0/0x1d30 net/ipv4/tcp_input.c:6115
 tcp_v4_do_rcv+0x784/0xa68 net/ipv4/tcp_ipv4.c:1692
 tcp_v4_rcv+0x1efc/0x24d0 net/ipv4/tcp_ipv4.c:2123
 ip_protocol_deliver_rcu+0x34c/0x780 net/ipv4/ip_input.c:205
 ip_local_deliver_finish+0x250/0x484 net/ipv4/ip_input.c:233
 NF_HOOK+0x2dc/0x36c include/linux/netfilter.h:302
 ip_local_deliver+0x120/0x190 net/ipv4/ip_input.c:254
 dst_input include/net/dst.h:463 [inline]
 ip_rcv_finish+0x220/0x24c net/ipv4/ip_input.c:449
 NF_HOOK+0x2dc/0x36c include/linux/netfilter.h:302
 ip_rcv+0x7c/0x9c net/ipv4/ip_input.c:569
 __netif_receive_skb_one_core net/core/dev.c:5619 [inline]
 __netif_receive_skb+0xd0/0x2b0 net/core/dev.c:5733
 process_backlog+0x42c/0x748 net/core/dev.c:6061
 __napi_poll+0xb8/0x3f4 net/core/dev.c:6628
 napi_poll net/core/dev.c:6695 [inline]
 net_rx_action+0x52c/0xb5c net/core/dev.c:6809
 handle_softirqs+0x318/0xc90 kernel/softirq.c:596
 __do_softirq+0x14/0x20 kernel/softirq.c:630
 ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:80
 call_on_irq_stack+0x30/0x48 arch/arm64/kernel/entry.S:897
 do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:85
 do_softirq+0xf8/0x1a0 kernel/softirq.c:497
 __local_bh_enable_ip+0x250/0x37c kernel/softirq.c:421
 local_bh_enable+0x28/0x34 include/linux/bottom_half.h:33
 rcu_read_unlock_bh include/linux/rcupdate.h:861 [inline]
 __dev_queue_xmit+0x16f8/0x3154 net/core/dev.c:4411
 dev_queue_xmit include/linux/netdevice.h:3053 [inline]
 neigh_hh_output include/net/neighbour.h:533 [inline]
 neigh_output include/net/neighbour.h:547 [inline]
 ip_finish_output2+0xc08/0x10a8 net/ipv4/ip_output.c:228
 __ip_finish_output+0x1b0/0x448 net/ipv4/ip_output.c:-1
 ip_finish_output+0x40/0x264 net/ipv4/ip_output.c:316
 NF_HOOK_COND include/linux/netfilter.h:291 [inline]
 ip_output+0x3b4/0x554 net/ipv4/ip_output.c:434
 dst_output include/net/dst.h:453 [inline]
 ip_local_out net/ipv4/ip_output.c:126 [inline]
 __ip_queue_xmit+0xcbc/0x1718 net/ipv4/ip_output.c:538
 ip_queue_xmit+0x5c/0x7c net/ipv4/ip_output.c:552
 __tcp_transmit_skb+0x17bc/0x2bcc net/ipv4/tcp_output.c:1407
 tcp_transmit_skb net/ipv4/tcp_output.c:1425 [inline]
 tcp_write_xmit+0x1118/0x4d8c net/ipv4/tcp_output.c:2722
 __tcp_push_pending_frames net/ipv4/tcp_output.c:2907 [inline]
 tcp_send_fin+0x550/0xac8 net/ipv4/tcp_output.c:3510
 __tcp_close+0x504/0xf08 net/ipv4/tcp.c:2993
 tcp_close+0x38/0x140 net/ipv4/tcp.c:3082
 inet_release+0x154/0x1cc net/ipv4/af_inet.c:430
 __sock_release net/socket.c:654 [inline]
 sock_release+0x88/0x144 net/socket.c:682
 smc_clcsock_release+0xc0/0xe8 net/smc/smc_close.c:34
 __smc_release+0x56c/0x6c0 net/smc/af_smc.c:314
 smc_release+0x258/0x514 net/smc/af_smc.c:357
 __sock_release net/socket.c:654 [inline]
 sock_close+0xac/0x1ec net/socket.c:1400
 __fput+0x1b4/0x7b0 fs/file_table.c:320
 ____fput+0x20/0x30 fs/file_table.c:348
 task_work_run+0x1f4/0x280 kernel/task_work.c:203
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 do_notify_resume+0x20f8/0x2c84 arch/arm64/kernel/signal.c:1151
 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
 exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
 el0_svc+0x98/0x128 arch/arm64/kernel/entry-common.c:638
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
Code: bad PC value
---[ end trace 0000000000000000 ]---