comedi comedi3: c6xdigio: I/O port conflict (0x4f2b,3)
==================================================================
BUG: KASAN: slab-use-after-free in sysfs_remove_file_ns+0x3d/0x70 fs/sysfs/file.c:491
Read of size 8 at addr ffff88807981ce30 by task syz.2.1094/9596

CPU: 0 PID: 9596 Comm: syz.2.1094 Not tainted 6.6.102-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xac/0x220 mm/kasan/report.c:468
 kasan_report+0x117/0x150 mm/kasan/report.c:581
 sysfs_remove_file_ns+0x3d/0x70 fs/sysfs/file.c:491
 remove_bind_files drivers/base/bus.c:602 [inline]
 bus_remove_driver+0x193/0x2f0 drivers/base/bus.c:740
 comedi_device_detach+0x131/0x6f0 drivers/comedi/drivers.c:206
 comedi_device_attach+0x561/0x660 drivers/comedi/drivers.c:1002
 do_devconfig_ioctl drivers/comedi/comedi_fops.c:855 [inline]
 comedi_unlocked_ioctl+0x68d/0xf90 drivers/comedi/comedi_fops.c:2156
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f6d42d8ebe9
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:00007f6d43b99038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f6d42fb6090 RCX: 00007f6d42d8ebe9
RDX: 00002000000000c0 RSI: 0000000040946400 RDI: 0000000000000006
RBP: 00007f6d42e11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6d42fb6128 R14: 00007f6d42fb6090 R15: 00007ffd879a3ca8
 </TASK>

Allocated by task 2:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:374 [inline]
 __kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:383
 kmalloc include/linux/slab.h:600 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 set_kthread_struct+0xb7/0x1f0 kernel/kthread.c:118
 copy_process+0x107a/0x3d70 kernel/fork.c:2433
 kernel_clone+0x21b/0x840 kernel/fork.c:2914
 kernel_thread+0x10d/0x160 kernel/fork.c:2976
 create_kthread kernel/kthread.c:411 [inline]
 kthreadd+0x560/0x730 kernel/kthread.c:766
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

Freed by task 16:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
 kasan_save_free_info+0x2e/0x50 mm/kasan/generic.c:522
 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:236
 kasan_slab_free include/linux/kasan.h:164 [inline]
 slab_free_hook mm/slub.c:1806 [inline]
 slab_free_freelist_hook+0x130/0x1b0 mm/slub.c:1832
 slab_free mm/slub.c:3816 [inline]
 __kmem_cache_free+0xba/0x1f0 mm/slub.c:3829
 free_task+0xe7/0x160 kernel/fork.c:626
 put_task_struct include/linux/sched/task.h:137 [inline]
 delayed_put_task_struct+0x10f/0x2b0 kernel/exit.c:226
 rcu_do_batch kernel/rcu/tree.c:2194 [inline]
 rcu_core+0xcc4/0x1720 kernel/rcu/tree.c:2467
 handle_softirqs+0x280/0x820 kernel/softirq.c:578
 run_ksoftirqd+0x9c/0xf0 kernel/softirq.c:950
 smpboot_thread_fn+0x635/0xa00 kernel/smpboot.c:164
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

Last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:45
 __kasan_record_aux_stack+0xaf/0xc0 mm/kasan/generic.c:492
 __call_rcu_common kernel/rcu/tree.c:2721 [inline]
 call_rcu+0x158/0x930 kernel/rcu/tree.c:2837
 fib_create_info+0x1845/0x2460 net/ipv4/fib_semantics.c:1590
 fib_table_insert+0xc7/0x1b50 net/ipv4/fib_trie.c:1217
 fib_magic+0x2c5/0x390 net/ipv4/fib_frontend.c:1118
 fib_add_ifaddr+0x144/0x5e0 net/ipv4/fib_frontend.c:1140
 fib_netdev_event+0x389/0x490 net/ipv4/fib_frontend.c:1500
 notifier_call_chain+0x197/0x390 kernel/notifier.c:93
 call_netdevice_notifiers_extack net/core/dev.c:2064 [inline]
 call_netdevice_notifiers net/core/dev.c:2078 [inline]
 __dev_notify_flags+0x18e/0x2e0 net/core/dev.c:-1
 dev_change_flags+0xe8/0x1a0 net/core/dev.c:8750
 do_setlink+0xc74/0x3fb0 net/core/rtnetlink.c:2905
 __rtnl_newlink net/core/rtnetlink.c:3703 [inline]
 rtnl_newlink+0x175b/0x2020 net/core/rtnetlink.c:3750
 rtnetlink_rcv_msg+0x7c7/0xf10 net/core/rtnetlink.c:6475
 netlink_rcv_skb+0x216/0x480 net/netlink/af_netlink.c:2555
 netlink_unicast_kernel net/netlink/af_netlink.c:1330 [inline]
 netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1356
 netlink_sendmsg+0x8c1/0xbe0 net/netlink/af_netlink.c:1904
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 __sys_sendto+0x46a/0x620 net/socket.c:2201
 __do_sys_sendto net/socket.c:2213 [inline]
 __se_sys_sendto net/socket.c:2209 [inline]
 __x64_sys_sendto+0xde/0xf0 net/socket.c:2209
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff88807981ce00
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 48 bytes inside of
 freed 256-byte region [ffff88807981ce00, ffff88807981cf00)

The buggy address belongs to the physical page:
page:ffffea0001e60700 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7981c
head:ffffea0001e60700 order:1 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000840 ffff888017841b40 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000100010 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 5786, tgid 5786 (syz-executor), ts 71321892813, free_ts 71292165219
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1cd/0x210 mm/page_alloc.c:1554
 prep_new_page mm/page_alloc.c:1561 [inline]
 get_page_from_freelist+0x195c/0x19f0 mm/page_alloc.c:3191
 __alloc_pages+0x1e3/0x460 mm/page_alloc.c:4457
 alloc_slab_page+0x5d/0x170 mm/slub.c:1876
 allocate_slab mm/slub.c:2023 [inline]
 new_slab+0x87/0x2e0 mm/slub.c:2076
 ___slab_alloc+0xc6d/0x12f0 mm/slub.c:3230
 __slab_alloc mm/slub.c:3329 [inline]
 __slab_alloc_node mm/slub.c:3382 [inline]
 slab_alloc_node mm/slub.c:3475 [inline]
 __kmem_cache_alloc_node+0x1a2/0x260 mm/slub.c:3524
 __do_kmalloc_node mm/slab_common.c:1006 [inline]
 __kmalloc+0xa4/0x240 mm/slab_common.c:1020
 kmalloc include/linux/slab.h:604 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 fib_create_info+0xa61/0x2460 net/ipv4/fib_semantics.c:1459
 fib_table_insert+0xc7/0x1b50 net/ipv4/fib_trie.c:1217
 fib_magic+0x2c5/0x390 net/ipv4/fib_frontend.c:1118
 fib_add_ifaddr+0x144/0x5e0 net/ipv4/fib_frontend.c:1140
 fib_inetaddr_event+0x140/0x1d0 net/ipv4/fib_frontend.c:1454
 notifier_call_chain+0x197/0x390 kernel/notifier.c:93
 blocking_notifier_call_chain+0x6a/0x90 kernel/notifier.c:388
 __inet_insert_ifa+0x9ae/0xbb0 net/ipv4/devinet.c:571
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1154 [inline]
 free_unref_page_prepare+0x7ce/0x8e0 mm/page_alloc.c:2336
 free_unref_page+0x32/0x2e0 mm/page_alloc.c:2429
 __slab_free+0x35e/0x410 mm/slub.c:3722
 qlink_free mm/kasan/quarantine.c:166 [inline]
 qlist_free_all+0x75/0xe0 mm/kasan/quarantine.c:185
 kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:305
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6e/0x4d0 mm/slab.h:767
 slab_alloc_node mm/slub.c:3485 [inline]
 __kmem_cache_alloc_node+0x13e/0x260 mm/slub.c:3524
 __do_kmalloc_node mm/slab_common.c:1006 [inline]
 __kmalloc_node+0xa4/0x230 mm/slab_common.c:1014
 kmalloc_node include/linux/slab.h:620 [inline]
 kvmalloc_node+0x70/0x180 mm/util.c:617
 kvmalloc include/linux/slab.h:738 [inline]
 kvzalloc include/linux/slab.h:746 [inline]
 bucket_table_alloc lib/rhashtable.c:184 [inline]
 rhashtable_rehash_alloc+0x9f/0x290 lib/rhashtable.c:363
 rht_deferred_worker+0x4f9/0x2410 lib/rhashtable.c:-1
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152

Memory state around the buggy address:
 ffff88807981cd00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88807981cd80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88807981ce00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                     ^
 ffff88807981ce80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88807981cf00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================