================================================================== BUG: KASAN: use-after-free in ax25_fillin_cb_from_dev net/ax25/af_ax25.c:468 [inline] BUG: KASAN: use-after-free in ax25_fillin_cb+0x394/0x568 net/ax25/af_ax25.c:495 Read of size 4 at addr ffff0000cdd05c38 by task syz.5.681/7120 CPU: 1 PID: 7120 Comm: syz.5.681 Not tainted 5.15.186-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Call trace: dump_backtrace+0x0/0x43c arch/arm64/kernel/stacktrace.c:152 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216 __dump_stack+0x30/0x40 lib/dump_stack.c:88 dump_stack_lvl+0xf8/0x160 lib/dump_stack.c:106 print_address_description+0x78/0x30c mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:434 [inline] kasan_report+0xec/0x15c mm/kasan/report.c:451 __asan_report_load4_noabort+0x44/0x50 mm/kasan/report_generic.c:308 ax25_fillin_cb_from_dev net/ax25/af_ax25.c:468 [inline] ax25_fillin_cb+0x394/0x568 net/ax25/af_ax25.c:495 ax25_setsockopt+0x8d0/0xa5c net/ax25/af_ax25.c:690 __sys_setsockopt+0x2f8/0x4b0 net/socket.c:2203 __do_sys_setsockopt net/socket.c:2214 [inline] __se_sys_setsockopt net/socket.c:2211 [inline] __arm64_sys_setsockopt+0xb8/0xd4 net/socket.c:2211 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 Allocated by task 6139: 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+0xb0/0xf0 mm/kasan/common.c:522 kasan_kmalloc include/linux/kasan.h:264 [inline] kmem_cache_alloc_trace+0x274/0x3fc mm/slub.c:3247 kmalloc include/linux/slab.h:604 [inline] kzalloc include/linux/slab.h:735 [inline] ax25_dev_device_up+0x5c/0x540 net/ax25/ax25_dev.c:55 ax25_device_event+0x504/0x590 net/ax25/af_ax25.c:139 notifier_call_chain kernel/notifier.c:83 [inline] raw_notifier_call_chain+0xd4/0x164 kernel/notifier.c:391 call_netdevice_notifiers_info net/core/dev.c:2049 [inline] call_netdevice_notifiers_extack net/core/dev.c:2061 [inline] call_netdevice_notifiers net/core/dev.c:2075 [inline] __dev_notify_flags+0x250/0x46c net/core/dev.c:-1 dev_change_flags+0xc8/0x154 net/core/dev.c:8929 dev_ifsioc+0x504/0xef4 net/core/dev_ioctl.c:324 dev_ioctl+0x4d0/0xc94 net/core/dev_ioctl.c:587 sock_do_ioctl+0x18c/0x240 net/socket.c:1154 sock_ioctl+0x5c8/0x87c net/socket.c:1257 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 Freed by task 7052: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track+0x4c/0x84 mm/kasan/common.c:46 kasan_set_free_info+0x28/0x4c mm/kasan/generic.c:360 ____kasan_slab_free+0x118/0x164 mm/kasan/common.c:366 __kasan_slab_free+0x18/0x28 mm/kasan/common.c:374 kasan_slab_free include/linux/kasan.h:230 [inline] slab_free_hook mm/slub.c:1705 [inline] slab_free_freelist_hook+0x128/0x1e8 mm/slub.c:1731 slab_free mm/slub.c:3499 [inline] kfree+0x170/0x40c mm/slub.c:4559 ax25_dev_put include/net/ax25.h:302 [inline] ax25_release+0x564/0x814 net/ax25/af_ax25.c:1062 __sock_release net/socket.c:649 [inline] sock_close+0xb4/0x1f8 net/socket.c:1336 __fput+0x1c0/0x7f8 fs/file_table.c:311 ____fput+0x20/0x30 fs/file_table.c:339 task_work_run+0x12c/0x1e0 kernel/task_work.c:188 tracehook_notify_resume include/linux/tracehook.h:189 [inline] do_notify_resume+0x24b4/0x3128 arch/arm64/kernel/signal.c:949 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline] exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline] el0_svc+0xf0/0x1e0 arch/arm64/kernel/entry-common.c:609 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 Last potentially related work creation: kasan_save_stack+0x38/0x68 mm/kasan/common.c:38 kasan_record_aux_stack+0xcc/0x114 mm/kasan/generic.c:348 kvfree_call_rcu+0xb8/0x66c kernel/rcu/tree.c:3596 ip_ma_put+0x118/0x1bc net/ipv4/igmp.c:171 __ip_mc_dec_group+0x52c/0x604 net/ipv4/igmp.c:1697 ip_mc_dec_group include/linux/igmp.h:135 [inline] ip_mc_down+0x2e4/0x3e0 net/ipv4/igmp.c:1752 inetdev_event+0x228/0x127c net/ipv4/devinet.c:1598 notifier_call_chain kernel/notifier.c:83 [inline] raw_notifier_call_chain+0xd4/0x164 kernel/notifier.c:391 call_netdevice_notifiers_info net/core/dev.c:2049 [inline] call_netdevice_notifiers_extack net/core/dev.c:2061 [inline] call_netdevice_notifiers net/core/dev.c:2075 [inline] dev_close_many+0x2cc/0x440 net/core/dev.c:1650 unregister_netdevice_many+0x3d4/0x17d0 net/core/dev.c:11110 unregister_netdevice_queue+0x2ac/0x2f8 net/core/dev.c:11067 unregister_netdevice include/linux/netdevice.h:3020 [inline] nsim_destroy+0x58/0x164 drivers/net/netdevsim/netdev.c:382 __nsim_dev_port_del+0x144/0x1a4 drivers/net/netdevsim/dev.c:1349 nsim_dev_port_del_all drivers/net/netdevsim/dev.c:1362 [inline] nsim_dev_reload_destroy+0x144/0x204 drivers/net/netdevsim/dev.c:1561 nsim_dev_reload_down+0xe8/0x154 drivers/net/netdevsim/dev.c:883 devlink_reload+0x1e8/0x5c8 net/core/devlink.c:3963 devlink_pernet_pre_exit+0x194/0x33c net/core/devlink.c:11543 ops_pre_exit_list net/core/net_namespace.c:162 [inline] cleanup_net+0x470/0xa98 net/core/net_namespace.c:615 process_one_work+0x79c/0x1140 kernel/workqueue.c:2310 worker_thread+0x8f4/0x101c kernel/workqueue.c:2457 kthread+0x374/0x454 kernel/kthread.c:334 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:855 Second to last potentially related work creation: kasan_save_stack+0x38/0x68 mm/kasan/common.c:38 kasan_record_aux_stack+0xcc/0x114 mm/kasan/generic.c:348 insert_work+0x64/0x388 kernel/workqueue.c:1366 __queue_work+0xb30/0x1054 kernel/workqueue.c:1532 queue_work_on+0xc4/0x17c kernel/workqueue.c:1559 queue_work include/linux/workqueue.h:512 [inline] call_usermodehelper_exec+0x22c/0x478 kernel/umh.c:435 kobject_uevent_env+0x670/0x888 lib/kobject_uevent.c:633 kobject_uevent+0x2c/0x3c lib/kobject_uevent.c:657 driver_register+0x29c/0x374 drivers/base/driver.c:248 __platform_driver_register+0x6c/0x80 drivers/base/platform.c:858 hns_mdio_driver_init+0x20/0x2c drivers/net/ethernet/hisilicon/hns_mdio.c:570 do_one_initcall+0x228/0x8b0 init/main.c:1302 do_initcall_level+0x154/0x214 init/main.c:1375 do_initcalls+0x58/0xac init/main.c:1391 do_basic_setup+0x8c/0xa0 init/main.c:1410 kernel_init_freeable+0x404/0x5fc init/main.c:1615 kernel_init+0x24/0x1d0 init/main.c:1506 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:855 The buggy address belongs to the object at ffff0000cdd05c00 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 56 bytes inside of 256-byte region [ffff0000cdd05c00, ffff0000cdd05d00) The buggy address belongs to the page: page:000000003d346ab7 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10dd04 head:000000003d346ab7 order:1 compound_mapcount:0 flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff) raw: 05ffc00000010200 fffffc00033ce380 0000000600000006 ffff0000c0002480 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0000cdd05b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff0000cdd05b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff0000cdd05c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff0000cdd05c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff0000cdd05d00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================