==================================================================
BUG: KASAN: use-after-free in hlist_add_head include/linux/list.h:814 [inline]
BUG: KASAN: use-after-free in enqueue_timer+0xb7/0x300 kernel/time/timer.c:541
Write of size 8 at addr ffff8881d9cf31c8 by task kworker/0:7/775

CPU: 0 PID: 775 Comm: kworker/0:7 Not tainted 5.4.276-syzkaller-00020-g4275fce9fe94 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Workqueue: ipv6_addrconf addrconf_dad_work
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1d8/0x241 lib/dump_stack.c:118
 print_address_description+0x8c/0x600 mm/kasan/report.c:384
 __kasan_report+0xf3/0x120 mm/kasan/report.c:516
 kasan_report+0x30/0x60 mm/kasan/common.c:653
 hlist_add_head include/linux/list.h:814 [inline]
 enqueue_timer+0xb7/0x300 kernel/time/timer.c:541
 __internal_add_timer kernel/time/timer.c:554 [inline]
 internal_add_timer+0x240/0x430 kernel/time/timer.c:604
 __mod_timer+0x6f1/0x13e0 kernel/time/timer.c:1065
 mod_delayed_work_on+0xff/0x190 kernel/workqueue.c:1736
 mod_delayed_work include/linux/workqueue.h:531 [inline]
 addrconf_mod_dad_work+0x79/0x120 net/ipv6/addrconf.c:326
 addrconf_dad_work+0xa80/0x16f0 net/ipv6/addrconf.c:4188
 process_one_work+0x765/0xd20 kernel/workqueue.c:2290
 worker_thread+0xaef/0x1470 kernel/workqueue.c:2436
 kthread+0x2da/0x360 kernel/kthread.c:288
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:354

Allocated by task 2272:
 save_stack mm/kasan/common.c:70 [inline]
 set_track mm/kasan/common.c:78 [inline]
 __kasan_kmalloc+0x171/0x210 mm/kasan/common.c:529
 slab_post_alloc_hook mm/slab.h:584 [inline]
 slab_alloc_node mm/slub.c:2829 [inline]
 slab_alloc mm/slub.c:2837 [inline]
 __kmalloc_track_caller+0x100/0x2b0 mm/slub.c:4449
 __kmalloc_reserve net/core/skbuff.c:142 [inline]
 __alloc_skb+0xb4/0x4d0 net/core/skbuff.c:210
 alloc_skb include/linux/skbuff.h:1080 [inline]
 nlmsg_new include/net/netlink.h:888 [inline]
 inet6_netconf_notify_devconf+0xc9/0x180 net/ipv6/addrconf.c:573
 __addrconf_sysctl_register+0x380/0x3e0 net/ipv6/addrconf.c:6973
 addrconf_sysctl_register+0x128/0x180 net/ipv6/addrconf.c:7010
 ipv6_add_dev+0xb34/0x10a0 net/ipv6/addrconf.c:444
 addrconf_notify+0x59b/0xe50 net/ipv6/addrconf.c:3555
 notifier_call_chain kernel/notifier.c:98 [inline]
 __raw_notifier_call_chain kernel/notifier.c:399 [inline]
 raw_notifier_call_chain+0x95/0x110 kernel/notifier.c:406
 call_netdevice_notifiers_info net/core/dev.c:1670 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:1682 [inline]
 call_netdevice_notifiers net/core/dev.c:1696 [inline]
 register_netdevice+0xeef/0x12a0 net/core/dev.c:9221
 veth_newlink+0x835/0xb50 drivers/net/veth.c:1329
 __rtnl_newlink net/core/rtnetlink.c:3255 [inline]
 rtnl_newlink+0x1567/0x2060 net/core/rtnetlink.c:3314
 rtnetlink_rcv_msg+0x983/0xc70 net/core/rtnetlink.c:5290
 netlink_rcv_skb+0x1d5/0x420 net/netlink/af_netlink.c:2481
 netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline]
 netlink_unicast+0x936/0xb20 net/netlink/af_netlink.c:1347
 netlink_sendmsg+0xa18/0xcf0 net/netlink/af_netlink.c:1915
 sock_sendmsg_nosec net/socket.c:638 [inline]
 __sock_sendmsg net/socket.c:650 [inline]
 __sys_sendto+0x4f3/0x6c0 net/socket.c:1961
 __do_sys_sendto net/socket.c:1973 [inline]
 __se_sys_sendto net/socket.c:1969 [inline]
 __x64_sys_sendto+0xda/0xf0 net/socket.c:1969
 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1

Freed by task 2272:
 save_stack mm/kasan/common.c:70 [inline]
 set_track mm/kasan/common.c:78 [inline]
 kasan_set_free_info mm/kasan/common.c:345 [inline]
 __kasan_slab_free+0x1b5/0x270 mm/kasan/common.c:487
 slab_free_hook mm/slub.c:1455 [inline]
 slab_free_freelist_hook mm/slub.c:1494 [inline]
 slab_free mm/slub.c:3080 [inline]
 kfree+0x123/0x370 mm/slub.c:4071
 skb_release_all net/core/skbuff.c:675 [inline]
 __kfree_skb net/core/skbuff.c:689 [inline]
 consume_skb+0xa5/0x2a0 net/core/skbuff.c:849
 netlink_broadcast_filtered+0x115f/0x1280 net/netlink/af_netlink.c:1531
 netlink_broadcast net/netlink/af_netlink.c:1553 [inline]
 nlmsg_multicast include/net/netlink.h:968 [inline]
 nlmsg_notify+0xf7/0x1b0 net/netlink/af_netlink.c:2524
 __addrconf_sysctl_register+0x380/0x3e0 net/ipv6/addrconf.c:6973
 addrconf_sysctl_register+0x128/0x180 net/ipv6/addrconf.c:7010
 ipv6_add_dev+0xb34/0x10a0 net/ipv6/addrconf.c:444
 addrconf_notify+0x59b/0xe50 net/ipv6/addrconf.c:3555
 notifier_call_chain kernel/notifier.c:98 [inline]
 __raw_notifier_call_chain kernel/notifier.c:399 [inline]
 raw_notifier_call_chain+0x95/0x110 kernel/notifier.c:406
 call_netdevice_notifiers_info net/core/dev.c:1670 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:1682 [inline]
 call_netdevice_notifiers net/core/dev.c:1696 [inline]
 register_netdevice+0xeef/0x12a0 net/core/dev.c:9221
 veth_newlink+0x835/0xb50 drivers/net/veth.c:1329
 __rtnl_newlink net/core/rtnetlink.c:3255 [inline]
 rtnl_newlink+0x1567/0x2060 net/core/rtnetlink.c:3314
 rtnetlink_rcv_msg+0x983/0xc70 net/core/rtnetlink.c:5290
 netlink_rcv_skb+0x1d5/0x420 net/netlink/af_netlink.c:2481
 netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline]
 netlink_unicast+0x936/0xb20 net/netlink/af_netlink.c:1347
 netlink_sendmsg+0xa18/0xcf0 net/netlink/af_netlink.c:1915
 sock_sendmsg_nosec net/socket.c:638 [inline]
 __sock_sendmsg net/socket.c:650 [inline]
 __sys_sendto+0x4f3/0x6c0 net/socket.c:1961
 __do_sys_sendto net/socket.c:1973 [inline]
 __se_sys_sendto net/socket.c:1969 [inline]
 __x64_sys_sendto+0xda/0xf0 net/socket.c:1969
 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1

The buggy address belongs to the object at ffff8881d9cf3000
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 456 bytes inside of
 512-byte region [ffff8881d9cf3000, ffff8881d9cf3200)
The buggy address belongs to the page:
page:ffffea0007673c00 refcount:1 mapcount:0 mapping:ffff8881f5c02500 index:0x0 compound_mapcount: 0
flags: 0x8000000000010200(slab|head)
raw: 8000000000010200 dead000000000100 dead000000000122 ffff8881f5c02500
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL)
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook mm/page_alloc.c:2165 [inline]
 prep_new_page+0x18f/0x370 mm/page_alloc.c:2171
 get_page_from_freelist+0x2d13/0x2d90 mm/page_alloc.c:3794
 __alloc_pages_nodemask+0x393/0x840 mm/page_alloc.c:4893
 alloc_slab_page+0x39/0x3c0 mm/slub.c:343
 allocate_slab mm/slub.c:1683 [inline]
 new_slab+0x97/0x440 mm/slub.c:1749
 new_slab_objects mm/slub.c:2505 [inline]
 ___slab_alloc+0x2fe/0x490 mm/slub.c:2667
 __slab_alloc+0x62/0xa0 mm/slub.c:2707
 slab_alloc_node mm/slub.c:2792 [inline]
 slab_alloc mm/slub.c:2837 [inline]
 __kmalloc+0x19b/0x2e0 mm/slub.c:3909
 kmalloc include/linux/slab.h:561 [inline]
 kzalloc include/linux/slab.h:690 [inline]
 new_dir fs/proc/proc_sysctl.c:973 [inline]
 get_subdir fs/proc/proc_sysctl.c:1018 [inline]
 __register_sysctl_table+0x983/0x11d0 fs/proc/proc_sysctl.c:1361
 __devinet_sysctl_register+0x1d3/0x2a0 net/ipv4/devinet.c:2588
 devinet_sysctl_register+0x13a/0x1a0 net/ipv4/devinet.c:2628
 inetdev_init+0x24e/0x450 net/ipv4/devinet.c:276
 inetdev_event+0x205/0x1040 net/ipv4/devinet.c:1531
 notifier_call_chain kernel/notifier.c:98 [inline]
 __raw_notifier_call_chain kernel/notifier.c:399 [inline]
 raw_notifier_call_chain+0x95/0x110 kernel/notifier.c:406
 call_netdevice_notifiers_info net/core/dev.c:1670 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:1682 [inline]
 call_netdevice_notifiers net/core/dev.c:1696 [inline]
 register_netdevice+0xeef/0x12a0 net/core/dev.c:9221
 veth_newlink+0x667/0xb50 drivers/net/veth.c:1302
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1176 [inline]
 __free_pages_ok+0x847/0x950 mm/page_alloc.c:1438
 free_the_page mm/page_alloc.c:4955 [inline]
 __free_pages+0x91/0x140 mm/page_alloc.c:4961
 device_release+0x6b/0x190 drivers/base/core.c:1776
 kobject_cleanup lib/kobject.c:716 [inline]
 kobject_release lib/kobject.c:747 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x1e6/0x2f0 lib/kobject.c:764
 tun_set_iff+0x870/0xdc0 drivers/net/tun.c:2921
 __tun_chr_ioctl+0x8a9/0x1d00 drivers/net/tun.c:3184
 do_vfs_ioctl+0x742/0x1720 fs/ioctl.c:47
 ksys_ioctl fs/ioctl.c:742 [inline]
 __do_sys_ioctl fs/ioctl.c:749 [inline]
 __se_sys_ioctl fs/ioctl.c:747 [inline]
 __x64_sys_ioctl+0xd4/0x110 fs/ioctl.c:747
 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1

Memory state around the buggy address:
 ffff8881d9cf3080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881d9cf3100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881d9cf3180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                              ^
 ffff8881d9cf3200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881d9cf3280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================