netlink: 4 bytes leftover after parsing attributes in process `syz.5.3170'.
==================================================================
BUG: KASAN: slab-use-after-free in sysfs_remove_file_ns+0x63/0x70 fs/sysfs/file.c:510
Read of size 8 at addr ffff888047ff5c30 by task syz.5.3170/16626

CPU: 2 UID: 0 PID: 16626 Comm: syz.5.3170 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 sysfs_remove_file_ns+0x63/0x70 fs/sysfs/file.c:510
 sysfs_remove_file include/linux/sysfs.h:770 [inline]
 driver_remove_file drivers/base/driver.c:201 [inline]
 driver_remove_file+0x4a/0x60 drivers/base/driver.c:197
 remove_bind_files drivers/base/bus.c:605 [inline]
 bus_remove_driver+0x224/0x2c0 drivers/base/bus.c:743
 driver_unregister+0x76/0xb0 drivers/base/driver.c:277
 comedi_device_detach_locked+0x12f/0xa50 drivers/comedi/drivers.c:207
 do_devconfig_ioctl+0x555/0x710 drivers/comedi/comedi_fops.c:848
 comedi_unlocked_ioctl+0x165d/0x2f00 drivers/comedi/comedi_fops.c:2178
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc18618eec9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc186fcd038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fc1863e6090 RCX: 00007fc18618eec9
RDX: 0000000000000000 RSI: 0000000040946400 RDI: 0000000000000008
RBP: 00007fc186211f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc1863e6128 R14: 00007fc1863e6090 R15: 00007ffc41566608
 </TASK>

Allocated by task 16549:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
 kasan_save_track+0x14/0x30 mm/kasan/common.c:77
 poison_kmalloc_redzone mm/kasan/common.c:400 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:417
 kasan_kmalloc include/linux/kasan.h:262 [inline]
 __do_kmalloc_node mm/slub.c:5627 [inline]
 __kmalloc_noprof+0x32f/0x880 mm/slub.c:5639
 kmalloc_noprof include/linux/slab.h:961 [inline]
 kzalloc_noprof include/linux/slab.h:1094 [inline]
 new_dir fs/proc/proc_sysctl.c:966 [inline]
 get_subdir fs/proc/proc_sysctl.c:1010 [inline]
 sysctl_mkdir_p fs/proc/proc_sysctl.c:1320 [inline]
 __register_sysctl_table+0xea2/0x1900 fs/proc/proc_sysctl.c:1395
 neigh_sysctl_register+0x31f/0x670 net/core/neighbour.c:3887
 addrconf_sysctl_register+0xb9/0x1f0 net/ipv6/addrconf.c:7367
 ipv6_add_dev+0xb31/0x15f0 net/ipv6/addrconf.c:460
 addrconf_notify+0x53e/0x19e0 net/ipv6/addrconf.c:3650
 notifier_call_chain+0xbc/0x410 kernel/notifier.c:85
 call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2229
 call_netdevice_notifiers_extack net/core/dev.c:2267 [inline]
 call_netdevice_notifiers net/core/dev.c:2281 [inline]
 register_netdevice+0x182e/0x2270 net/core/dev.c:11332
 macvlan_common_newlink+0x10e7/0x1a20 drivers/net/macvlan.c:1540
 rtnl_newlink_create net/core/rtnetlink.c:3833 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3950 [inline]
 rtnl_newlink+0xc45/0x2000 net/core/rtnetlink.c:4065
 rtnetlink_rcv_msg+0x95e/0xe90 net/core/rtnetlink.c:6954
 netlink_rcv_skb+0x158/0x420 net/netlink/af_netlink.c:2552
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8c8/0xdd0 net/netlink/af_netlink.c:1896
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 ____sys_sendmsg+0xa98/0xc70 net/socket.c:2630
 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2684
 __sys_sendmsg+0x16d/0x220 net/socket.c:2716
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 46:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
 kasan_save_track+0x14/0x30 mm/kasan/common.c:77
 __kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:587
 kasan_save_free_info mm/kasan/kasan.h:406 [inline]
 poison_slab_object mm/kasan/common.c:252 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:284
 kasan_slab_free include/linux/kasan.h:234 [inline]
 slab_free_hook mm/slub.c:2523 [inline]
 slab_free_freelist_hook mm/slub.c:2552 [inline]
 slab_free_bulk mm/slub.c:6643 [inline]
 kmem_cache_free_bulk mm/slub.c:7327 [inline]
 kmem_cache_free_bulk+0x419/0x8e0 mm/slub.c:7306
 kfree_bulk include/linux/slab.h:830 [inline]
 kvfree_rcu_bulk+0x1b7/0x1e0 mm/slab_common.c:1522
 kfree_rcu_work+0x124/0x1a0 mm/slab_common.c:1600
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3263
 process_scheduled_works kernel/workqueue.c:3346 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3427
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Last potentially related work creation:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
 kasan_record_aux_stack+0xa7/0xc0 mm/kasan/generic.c:559
 kvfree_call_rcu+0x86/0x520 mm/slab_common.c:1995
 drop_sysctl_table+0x355/0x5f0 fs/proc/proc_sysctl.c:1521
 unregister_sysctl_table fs/proc/proc_sysctl.c:1542 [inline]
 unregister_sysctl_table+0x41/0x60 fs/proc/proc_sysctl.c:1534
 neigh_sysctl_unregister+0x5f/0x80 net/core/neighbour.c:3908
 addrconf_ifdown.isra.0+0x1498/0x1aa0 net/ipv6/addrconf.c:4006
 addrconf_notify+0x220/0x19e0 net/ipv6/addrconf.c:3776
 notifier_call_chain+0xbc/0x410 kernel/notifier.c:85
 call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2229
 call_netdevice_notifiers_extack net/core/dev.c:2267 [inline]
 call_netdevice_notifiers net/core/dev.c:2281 [inline]
 unregister_netdevice_many_notify+0xf76/0x24c0 net/core/dev.c:12254
 rtnl_newlink_create net/core/rtnetlink.c:3861 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3950 [inline]
 rtnl_newlink+0x171e/0x2000 net/core/rtnetlink.c:4065
 rtnetlink_rcv_msg+0x95e/0xe90 net/core/rtnetlink.c:6954
 netlink_rcv_skb+0x158/0x420 net/netlink/af_netlink.c:2552
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8c8/0xdd0 net/netlink/af_netlink.c:1896
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 ____sys_sendmsg+0xa98/0xc70 net/socket.c:2630
 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2684
 __sys_sendmsg+0x16d/0x220 net/socket.c:2716
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888047ff5c00
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 48 bytes inside of
 freed 256-byte region [ffff888047ff5c00, ffff888047ff5d00)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x47ff4
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
ksm flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801b442b40 ffffea0000ebfc00 dead000000000003
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801b442b40 ffffea0000ebfc00 dead000000000003
head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000001 ffffea00011ffd01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5939, tgid 5939 (syz-executor), ts 54646178374, free_ts 54423381345
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1850
 prep_new_page mm/page_alloc.c:1858 [inline]
 get_page_from_freelist+0x10a3/0x3a30 mm/page_alloc.c:3884
 __alloc_frozen_pages_noprof+0x25f/0x2470 mm/page_alloc.c:5183
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
 alloc_slab_page mm/slub.c:3039 [inline]
 allocate_slab mm/slub.c:3212 [inline]
 new_slab+0x24a/0x360 mm/slub.c:3266
 ___slab_alloc+0xdc4/0x1ae0 mm/slub.c:4636
 __slab_alloc.constprop.0+0x63/0x110 mm/slub.c:4755
 __slab_alloc_node mm/slub.c:4831 [inline]
 slab_alloc_node mm/slub.c:5253 [inline]
 __kmalloc_cache_noprof+0x477/0x780 mm/slub.c:5743
 kmalloc_noprof include/linux/slab.h:957 [inline]
 kzalloc_noprof include/linux/slab.h:1094 [inline]
 ____ip_mc_inc_group+0x403/0x10f0 net/ipv4/igmp.c:1535
 __ip_mc_inc_group net/ipv4/igmp.c:1573 [inline]
 ip_mc_inc_group net/ipv4/igmp.c:1579 [inline]
 ip_mc_up+0x154/0x3b0 net/ipv4/igmp.c:1880
 inetdev_event+0xafb/0x18a0 net/ipv4/devinet.c:1630
 notifier_call_chain+0xbc/0x410 kernel/notifier.c:85
 call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2229
 call_netdevice_notifiers_extack net/core/dev.c:2267 [inline]
 call_netdevice_notifiers net/core/dev.c:2281 [inline]
 __dev_notify_flags+0x12c/0x2e0 net/core/dev.c:9676
 netif_change_flags+0x108/0x160 net/core/dev.c:9705
 do_setlink.constprop.0+0xb53/0x4380 net/core/rtnetlink.c:3151
page last free pid 6008 tgid 6008 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1394 [inline]
 __free_frozen_pages+0x7df/0x1160 mm/page_alloc.c:2906
 discard_slab mm/slub.c:3310 [inline]
 __put_partials+0x130/0x170 mm/slub.c:3857
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x4d/0x120 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x195/0x1e0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:352
 kasan_slab_alloc include/linux/kasan.h:252 [inline]
 slab_post_alloc_hook mm/slub.c:4955 [inline]
 slab_alloc_node mm/slub.c:5265 [inline]
 kmem_cache_alloc_noprof+0x250/0x6e0 mm/slub.c:5272
 vm_area_dup+0x27/0x8d0 mm/vma_init.c:123
 __split_vma+0x18e/0x1070 mm/vma.c:515
 vms_gather_munmap_vmas+0x3aa/0x1340 mm/vma.c:1380
 __mmap_prepare mm/vma.c:2359 [inline]
 __mmap_region+0x434/0x27a0 mm/vma.c:2652
 mmap_region+0x1ab/0x3f0 mm/vma.c:2740
 do_mmap+0xa3e/0x1210 mm/mmap.c:558
 vm_mmap_pgoff+0x29e/0x470 mm/util.c:581
 ksys_mmap_pgoff+0x32c/0x5c0 mm/mmap.c:604
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline]
 __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94

Memory state around the buggy address:
 ffff888047ff5b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888047ff5b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888047ff5c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                     ^
 ffff888047ff5c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888047ff5d00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================