==================================================================
BUG: KASAN: use-after-free in ax25_heartbeat_expiry+0x10c/0x130 net/ax25/ax25_timer.c:125
Read of size 4 at addr ffff88805fed0f50 by task syz-executor/4185

CPU: 1 PID: 4185 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <IRQ>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 ax25_heartbeat_expiry+0x10c/0x130 net/ax25/ax25_timer.c:125
 call_timer_fn+0x17b/0x540 kernel/time/timer.c:1648
 expire_timers kernel/time/timer.c:1699 [inline]
 __run_timers+0x53e/0x800 kernel/time/timer.c:1970
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1983
 handle_softirqs+0x339/0x830 kernel/softirq.c:576
 __do_softirq kernel/softirq.c:610 [inline]
 invoke_softirq kernel/softirq.c:450 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:get_current arch/x86/include/asm/current.h:15 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:226 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp8+0x4/0x80 kernel/kcov.c:300
Code: 77 22 89 ff 89 f6 4a c7 44 02 08 05 00 00 00 4a 89 7c 02 10 4a 89 74 02 18 4a 89 44 02 20 48 ff c1 48 89 0a c3 90 48 8b 04 24 <65> 48 8b 0d c4 4a 89 7e 65 8b 15 c5 4a 89 7e 81 e2 00 01 ff 00 74
RSP: 0018:ffffc90002e2f698 EFLAGS: 00000246
RAX: ffffffff81ad5b32 RBX: 0000000000000000 RCX: ffff88807ca63b80
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90002e2f950 R08: ffffea0001a42cb3 R09: 1ffffd4000348596
R10: dffffc0000000000 R11: fffff94000348597 R12: 00007ff147a79000
R13: 1ffffd4000348591 R14: 00fff00000000000 R15: 0000000000000000
 _compound_head include/linux/page-flags.h:198 [inline]
 PageSwapBacked include/linux/page-flags.h:371 [inline]
 mm_counter_file include/linux/mm.h:1977 [inline]
 mm_counter include/linux/mm.h:1986 [inline]
 copy_present_pte mm/memory.c:967 [inline]
 copy_pte_range mm/memory.c:1081 [inline]
 copy_pmd_range mm/memory.c:1167 [inline]
 copy_pud_range mm/memory.c:1204 [inline]
 copy_p4d_range mm/memory.c:1228 [inline]
 copy_page_range+0x1752/0x3230 mm/memory.c:1301
 dup_mmap kernel/fork.c:615 [inline]
 dup_mm kernel/fork.c:1466 [inline]
 copy_mm+0xc86/0x13f0 kernel/fork.c:1518
 copy_process+0x17eb/0x3e20 kernel/fork.c:2290
 kernel_clone+0x23f/0x990 kernel/fork.c:2679
 __do_sys_clone kernel/fork.c:2796 [inline]
 __se_sys_clone kernel/fork.c:2780 [inline]
 __x64_sys_clone+0x19a/0x210 kernel/fork.c:2780
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7ff14879e212
Code: 89 e7 e8 71 8b f7 ff 45 31 c0 31 d2 31 f6 64 48 8b 04 25 10 00 00 00 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 66 89 c5 85 c0 75 3b 64 48 8b 04 25 10 00 00
RSP: 002b:00007ffc30baa310 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007ffc30baa310 RCX: 00007ff14879e212
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 00007ffc30baa49c R08: 0000000000000000 R09: 0000000000000001
R10: 000055556777c7d0 R11: 0000000000000246 R12: 0000000000000001
R13: 00000000000927c0 R14: 0000000000032e7b R15: 00007ffc30baa4f0
 </TASK>

Allocated by task 4981:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 ____kasan_kmalloc mm/kasan/common.c:513 [inline]
 __kasan_kmalloc+0xb5/0xf0 mm/kasan/common.c:522
 kmalloc include/linux/slab.h:607 [inline]
 kzalloc include/linux/slab.h:738 [inline]
 ax25_dev_device_up+0x50/0x580 net/ax25/ax25_dev.c:55
 ax25_device_event+0x483/0x4f0 net/ax25/af_ax25.c:139
 notifier_call_chain kernel/notifier.c:83 [inline]
 raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:391
 call_netdevice_notifiers_extack net/core/dev.c:2074 [inline]
 call_netdevice_notifiers net/core/dev.c:2088 [inline]
 __dev_notify_flags+0x194/0x300 net/core/dev.c:8917
 dev_change_flags+0xe3/0x1a0 net/core/dev.c:8955
 dev_ifsioc+0x130/0xd50 net/core/dev_ioctl.c:324
 dev_ioctl+0x545/0xe30 net/core/dev_ioctl.c:572
 sock_do_ioctl+0x245/0x320 net/socket.c:1161
 sock_ioctl+0x4d2/0x710 net/socket.c:1266
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

Freed by task 5846:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:46
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
 ____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1710 [inline]
 slab_free_freelist_hook+0xea/0x170 mm/slub.c:1736
 slab_free mm/slub.c:3504 [inline]
 kfree+0xef/0x2a0 mm/slub.c:4564
 ax25_dev_put include/net/ax25.h:302 [inline]
 ax25_release+0x661/0x870 net/ax25/af_ax25.c:1062
 __sock_release net/socket.c:651 [inline]
 sock_close+0xd5/0x240 net/socket.c:1345
 __fput+0x234/0x930 fs/file_table.c:311
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 exit_task_work include/linux/task_work.h:33 [inline]
 do_exit+0x626/0x20c0 kernel/exit.c:883
 do_group_exit+0x12e/0x300 kernel/exit.c:997
 get_signal+0x6ca/0x12c0 kernel/signal.c:2900
 arch_do_signal_or_restart+0xe7/0x12c0 arch/x86/kernel/signal.c:867
 handle_signal_work kernel/entry/common.c:154 [inline]
 exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

Last potentially related work creation:
 kasan_save_stack+0x35/0x60 mm/kasan/common.c:38
 kasan_record_aux_stack+0xb8/0x100 mm/kasan/generic.c:348
 __call_rcu kernel/rcu/tree.c:3011 [inline]
 call_rcu+0x189/0x950 kernel/rcu/tree.c:3091
 nf_hook_entries_free net/netfilter/core.c:88 [inline]
 __nf_register_net_hook+0x6fe/0x850 net/netfilter/core.c:419
 nf_register_net_hook+0xae/0x190 net/netfilter/core.c:536
 nf_register_net_hooks+0x40/0x1a0 net/netfilter/core.c:552
 ip6t_register_table+0x551/0x810 net/ipv6/netfilter/ip6_tables.c:1789
 ip6table_raw_table_init+0x50/0x70 net/ipv6/netfilter/ip6table_raw.c:56
 xt_find_table_lock+0x220/0x360 net/netfilter/x_tables.c:1259
 xt_request_find_table_lock+0x22/0x100 net/netfilter/x_tables.c:1284
 get_info net/ipv6/netfilter/ip6_tables.c:981 [inline]
 do_ip6t_get_ctl+0x5e8/0x1120 net/ipv6/netfilter/ip6_tables.c:1670
 nf_getsockopt+0x25e/0x280 net/netfilter/nf_sockopt.c:116
 ipv6_getsockopt+0x473/0x2470 net/ipv6/ipv6_sockglue.c:1492
 tcp_getsockopt+0x200/0x25a0 net/ipv4/tcp.c:4322
 __sys_getsockopt+0x1b0/0x230 net/socket.c:2256
 __do_sys_getsockopt net/socket.c:2271 [inline]
 __se_sys_getsockopt net/socket.c:2268 [inline]
 __x64_sys_getsockopt+0xb1/0xc0 net/socket.c:2268
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

The buggy address belongs to the object at ffff88805fed0f00
 which belongs to the cache kmalloc-192 of size 192
The buggy address is located 80 bytes inside of
 192-byte region [ffff88805fed0f00, ffff88805fed0fc0)
The buggy address belongs to the page:
page:ffffea00017fb400 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88805fed0700 pfn:0x5fed0
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea00008828c8 ffffea00008aed88 ffff888016c41a00
raw: ffff88805fed0700 000000000010000b 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 4190, ts 59167104698, free_ts 59163754432
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x1bbd/0x1ca0 mm/page_alloc.c:4192
 __alloc_pages+0x1ee/0x480 mm/page_alloc.c:5501
 alloc_slab_page mm/slub.c:1780 [inline]
 allocate_slab mm/slub.c:1917 [inline]
 new_slab+0xc0/0x4b0 mm/slub.c:1980
 ___slab_alloc+0x80a/0xdd0 mm/slub.c:3013
 __slab_alloc mm/slub.c:3100 [inline]
 slab_alloc_node mm/slub.c:3191 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 kmem_cache_alloc_trace+0x1a5/0x2a0 mm/slub.c:3250
 kmalloc include/linux/slab.h:607 [inline]
 kzalloc include/linux/slab.h:738 [inline]
 kset_create lib/kobject.c:982 [inline]
 kset_create_and_add+0x56/0x160 lib/kobject.c:1025
 register_queue_kobjects net/core/net-sysfs.c:1759 [inline]
 netdev_register_kobject+0x1ae/0x320 net/core/net-sysfs.c:2018
 register_netdevice+0x1042/0x1710 net/core/dev.c:10423
 cfg80211_register_netdevice+0x155/0x2f0 net/wireless/core.c:1426
 ieee80211_if_add+0x1022/0x1dc0 net/mac80211/iface.c:2078
 ieee80211_register_hw+0x2bde/0x3af0 net/mac80211/main.c:1323
 mac80211_hwsim_new_radio+0x20d3/0x4080 drivers/net/wireless/mac80211_hwsim.c:3374
 hwsim_new_radio_nl+0xa6f/0xc40 drivers/net/wireless/mac80211_hwsim.c:3950
 genl_family_rcv_msg_doit net/netlink/genetlink.c:731 [inline]
 genl_family_rcv_msg net/netlink/genetlink.c:775 [inline]
 genl_rcv_msg+0xcea/0xf90 net/netlink/genetlink.c:792
 netlink_rcv_skb+0x1f5/0x440 net/netlink/af_netlink.c:2507
 genl_rcv+0x24/0x40 net/netlink/genetlink.c:803
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317
 free_unref_page+0x8f/0x2a0 mm/page_alloc.c:3396
 mm_free_pgd kernel/fork.c:653 [inline]
 __mmdrop+0xaa/0x3e0 kernel/fork.c:704
 exit_mm+0x588/0x6e0 kernel/exit.c:550
 do_exit+0x5a9/0x20c0 kernel/exit.c:870
 do_group_exit+0x12e/0x300 kernel/exit.c:997
 __do_sys_exit_group kernel/exit.c:1008 [inline]
 __se_sys_exit_group kernel/exit.c:1006 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1006
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

Memory state around the buggy address:
 ffff88805fed0e00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88805fed0e80: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
>ffff88805fed0f00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                 ^
 ffff88805fed0f80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff88805fed1000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
vkms_vblank_simulate: vblank timer overrun
----------------
Code disassembly (best guess):
   0:	77 22                	ja     0x24
   2:	89 ff                	mov    %edi,%edi
   4:	89 f6                	mov    %esi,%esi
   6:	4a c7 44 02 08 05 00 	movq   $0x5,0x8(%rdx,%r8,1)
   d:	00 00
   f:	4a 89 7c 02 10       	mov    %rdi,0x10(%rdx,%r8,1)
  14:	4a 89 74 02 18       	mov    %rsi,0x18(%rdx,%r8,1)
  19:	4a 89 44 02 20       	mov    %rax,0x20(%rdx,%r8,1)
  1e:	48 ff c1             	inc    %rcx
  21:	48 89 0a             	mov    %rcx,(%rdx)
  24:	c3                   	ret
  25:	90                   	nop
  26:	48 8b 04 24          	mov    (%rsp),%rax
* 2a:	65 48 8b 0d c4 4a 89 	mov    %gs:0x7e894ac4(%rip),%rcx        # 0x7e894af6 <-- trapping instruction
  31:	7e
  32:	65 8b 15 c5 4a 89 7e 	mov    %gs:0x7e894ac5(%rip),%edx        # 0x7e894afe
  39:	81 e2 00 01 ff 00    	and    $0xff0100,%edx
  3f:	74                   	.byte 0x74