syzbot

netlink: 'syz.3.371': attribute type 4 has an invalid length.
==================================================================
BUG: KASAN: use-after-free in sysfs_remove_file_ns+0x39/0x70 fs/sysfs/file.c:491
Read of size 8 at addr ffff888079e34630 by task syz.3.371/5739

CPU: 0 PID: 5739 Comm: syz.3.371 Not tainted 6.1.146-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:316 [inline]
 print_report+0xa8/0x200 mm/kasan/report.c:418
 kasan_report+0x10b/0x140 mm/kasan/report.c:522
 sysfs_remove_file_ns+0x39/0x70 fs/sysfs/file.c:491
 remove_bind_files drivers/base/bus.c:550 [inline]
 bus_remove_driver+0x89/0x230 drivers/base/bus.c:674
 comedi_device_detach+0x12d/0x6e0 drivers/comedi/drivers.c:206
 do_devconfig_ioctl drivers/comedi/comedi_fops.c:829 [inline]
 comedi_unlocked_ioctl+0xbd0/0xe90 drivers/comedi/comedi_fops.c:2131
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fe2daf8e9a9
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:00007fe2dbd4d038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fe2db1b6080 RCX: 00007fe2daf8e9a9
RDX: 0000000000000000 RSI: 0000000040946400 RDI: 0000000000000003
RBP: 00007fe2db010d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fe2db1b6080 R15: 00007ffcd1b45278
 </TASK>

Allocated by task 4714:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:374 [inline]
 __kasan_kmalloc+0x8e/0xa0 mm/kasan/common.c:383
 kmalloc include/linux/slab.h:563 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 bus_add_driver+0xda/0x5a0 drivers/base/bus.c:604
 driver_register+0x32d/0x430 drivers/base/driver.c:246
 c6xdigio_attach+0x90/0x880 drivers/comedi/drivers/c6xdigio.c:253
 comedi_device_attach+0x515/0x650 drivers/comedi/drivers.c:995
 do_devconfig_ioctl drivers/comedi/comedi_fops.c:851 [inline]
 comedi_unlocked_ioctl+0x5ec/0xe90 drivers/comedi/comedi_fops.c:2131
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Freed by task 5702:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:52
 kasan_save_free_info+0x2d/0x50 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:236
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1724 [inline]
 slab_free_freelist_hook+0x131/0x1a0 mm/slub.c:1750
 slab_free mm/slub.c:3661 [inline]
 __kmem_cache_free+0xb6/0x1f0 mm/slub.c:3674
 kobject_cleanup lib/kobject.c:681 [inline]
 kobject_release lib/kobject.c:712 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x21d/0x460 lib/kobject.c:729
 bus_remove_driver+0x13c/0x230 drivers/base/bus.c:681
 comedi_device_detach+0x12d/0x6e0 drivers/comedi/drivers.c:206
 do_devconfig_ioctl drivers/comedi/comedi_fops.c:829 [inline]
 comedi_unlocked_ioctl+0xbd0/0xe90 drivers/comedi/comedi_fops.c:2131
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Last potentially related work creation:
 kasan_save_stack+0x3a/0x60 mm/kasan/common.c:45
 __kasan_record_aux_stack+0xb2/0xc0 mm/kasan/generic.c:486
 call_rcu+0x154/0x980 kernel/rcu/tree.c:2849
 fib_create_info+0x1871/0x2490 net/ipv4/fib_semantics.c:1591
 fib_table_insert+0xc3/0x1b50 net/ipv4/fib_trie.c:1217
 fib_magic+0x2c1/0x390 net/ipv4/fib_frontend.c:1118
 fib_add_ifaddr+0x140/0x5e0 net/ipv4/fib_frontend.c:1140
 fib_netdev_event+0x361/0x470 net/ipv4/fib_frontend.c:1500
 notifier_call_chain kernel/notifier.c:87 [inline]
 raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:455
 call_netdevice_notifiers_extack net/core/dev.c:2039 [inline]
 call_netdevice_notifiers net/core/dev.c:2053 [inline]
 __dev_notify_flags+0x178/0x2d0 net/core/dev.c:-1
 dev_change_flags+0xe3/0x1a0 net/core/dev.c:8702
 do_setlink+0xc31/0x3c40 net/core/rtnetlink.c:2833
 __rtnl_newlink net/core/rtnetlink.c:3608 [inline]
 rtnl_newlink+0x17d6/0x1ff0 net/core/rtnetlink.c:3655
 rtnetlink_rcv_msg+0x79b/0xed0 net/core/rtnetlink.c:6153
 netlink_rcv_skb+0x1de/0x420 net/netlink/af_netlink.c:2511
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x74d/0x8d0 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x89e/0xbc0 net/netlink/af_netlink.c:1872
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 __sys_sendto+0x44f/0x5c0 net/socket.c:2153
 __do_sys_sendto net/socket.c:2165 [inline]
 __se_sys_sendto net/socket.c:2161 [inline]
 __x64_sys_sendto+0xda/0xf0 net/socket.c:2161
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff888079e34600
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 48 bytes inside of
 256-byte region [ffff888079e34600, ffff888079e34700)

The buggy address belongs to the physical page:
page:ffffea0001e78d00 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888079e35400 pfn:0x79e34
head:ffffea0001e78d00 order:1 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 ffffea0001e65088 ffffea0001f27c88 ffff888017441b40
raw: ffff888079e35400 000000000010000f 00000001ffffffff 0000000000000000
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 4264, tgid 4264 (syz-executor), ts 65185793732, free_ts 65151042205
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2532
 prep_new_page mm/page_alloc.c:2539 [inline]
 get_page_from_freelist+0x1a26/0x1ac0 mm/page_alloc.c:4328
 __alloc_pages+0x1df/0x4e0 mm/page_alloc.c:5614
 alloc_slab_page+0x5d/0x160 mm/slub.c:1794
 allocate_slab mm/slub.c:1939 [inline]
 new_slab+0x87/0x2c0 mm/slub.c:1992
 ___slab_alloc+0xbc6/0x1220 mm/slub.c:3180
 __slab_alloc mm/slub.c:3279 [inline]
 slab_alloc_node mm/slub.c:3364 [inline]
 __kmem_cache_alloc_node+0x1a0/0x260 mm/slub.c:3437
 __do_kmalloc_node mm/slab_common.c:935 [inline]
 __kmalloc+0xa0/0x240 mm/slab_common.c:949
 kmalloc include/linux/slab.h:568 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 fib_create_info+0xa53/0x2490 net/ipv4/fib_semantics.c:1459
 fib_table_insert+0xc3/0x1b50 net/ipv4/fib_trie.c:1217
 fib_magic+0x2c1/0x390 net/ipv4/fib_frontend.c:1118
 fib_add_ifaddr+0x3f7/0x5e0 net/ipv4/fib_frontend.c:1162
 fib_netdev_event+0x361/0x470 net/ipv4/fib_frontend.c:1500
 notifier_call_chain kernel/notifier.c:87 [inline]
 raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:455
 call_netdevice_notifiers_extack net/core/dev.c:2039 [inline]
 call_netdevice_notifiers net/core/dev.c:2053 [inline]
 __dev_notify_flags+0x178/0x2d0 net/core/dev.c:-1
 dev_change_flags+0xe3/0x1a0 net/core/dev.c:8702
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1459 [inline]
 free_pcp_prepare mm/page_alloc.c:1509 [inline]
 free_unref_page_prepare+0x8b4/0x9a0 mm/page_alloc.c:3384
 free_unref_page+0x2e/0x3f0 mm/page_alloc.c:3479
 qlink_free mm/kasan/quarantine.c:168 [inline]
 qlist_free_all+0x76/0xe0 mm/kasan/quarantine.c:187
 kasan_quarantine_reduce+0x144/0x160 mm/kasan/quarantine.c:294
 __kasan_slab_alloc+0x1e/0x80 mm/kasan/common.c:305
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook+0x4b/0x480 mm/slab.h:737
 slab_alloc_node mm/slub.c:3398 [inline]
 __kmem_cache_alloc_node+0x140/0x260 mm/slub.c:3437
 __do_kmalloc_node mm/slab_common.c:935 [inline]
 __kmalloc+0xa0/0x240 mm/slab_common.c:949
 kmalloc include/linux/slab.h:568 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 fib6_info_alloc+0x2e/0xe0 net/ipv6/ip6_fib.c:156
 ip6_route_info_create+0x44f/0x1210 net/ipv6/route.c:3794
 ip6_route_add+0x24/0x130 net/ipv6/route.c:3890
 addrconf_add_mroute net/ipv6/addrconf.c:2507 [inline]
 addrconf_add_dev+0x253/0x330 net/ipv6/addrconf.c:2525
 addrconf_dev_config net/ipv6/addrconf.c:3425 [inline]
 addrconf_init_auto_addrs+0x601/0xa60 net/ipv6/addrconf.c:3513
 addrconf_notify+0xaca/0xf40 net/ipv6/addrconf.c:3686
 notifier_call_chain kernel/notifier.c:87 [inline]
 raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:455
 netdev_state_change+0xd2/0x140 net/core/dev.c:1390

Memory state around the buggy address:
 ffff888079e34500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888079e34580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888079e34600: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                     ^
 ffff888079e34680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888079e34700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================