comedi comedi1: c6xdigio: I/O port conflict (0x401,3)
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BUG: KASAN: use-after-free in sysfs_remove_file_ns+0x3d/0x70 fs/sysfs/file.c:522
Read of size 8 at addr ffff8880247b2e30 by task syz.4.509/8118

CPU: 0 UID: 0 PID: 8118 Comm: syz.4.509 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 sysfs_remove_file_ns+0x3d/0x70 fs/sysfs/file.c:522
 remove_bind_files drivers/base/bus.c:605 [inline]
 bus_remove_driver+0x198/0x2f0 drivers/base/bus.c:743
 comedi_device_detach_locked+0x178/0x750 drivers/comedi/drivers.c:207
 comedi_device_detach drivers/comedi/drivers.c:215 [inline]
 comedi_device_attach+0x5d4/0x720 drivers/comedi/drivers.c:1011
 do_devconfig_ioctl drivers/comedi/comedi_fops.c:872 [inline]
 comedi_unlocked_ioctl+0x5ff/0x1020 drivers/comedi/comedi_fops.c:2178
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:598 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:584
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7a5eb8eec9
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:00007f7a5f964038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f7a5ede6090 RCX: 00007f7a5eb8eec9
RDX: 0000200000000080 RSI: 0000000040946400 RDI: 0000000000000003
RBP: 00007f7a5ec11f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7a5ede6128 R14: 00007f7a5ede6090 R15: 00007ffc1d9b8998
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff8880247b3400 pfn:0x247b2
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 dead000000000100 dead000000000122 0000000000000000
raw: ffff8880247b3400 0000000000100000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 7137, tgid 7137 (udevd), ts 232903231674, free_ts 248414787440
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5148
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416
 alloc_slab_page mm/slub.c:2492 [inline]
 allocate_slab+0x8a/0x370 mm/slub.c:2660
 new_slab mm/slub.c:2714 [inline]
 ___slab_alloc+0xbeb/0x1420 mm/slub.c:3901
 __slab_alloc mm/slub.c:3992 [inline]
 __slab_alloc_node mm/slub.c:4067 [inline]
 slab_alloc_node mm/slub.c:4228 [inline]
 kmem_cache_alloc_noprof+0x283/0x3c0 mm/slub.c:4247
 mt_alloc_one lib/maple_tree.c:176 [inline]
 mas_alloc_nodes+0x2e9/0x8e0 lib/maple_tree.c:1255
 mas_node_count_gfp lib/maple_tree.c:1337 [inline]
 mas_preallocate+0x3ad/0x6f0 lib/maple_tree.c:5537
 vma_iter_prealloc mm/vma.h:462 [inline]
 __split_vma+0x2fa/0xa00 mm/vma.c:528
 vms_gather_munmap_vmas+0x4ce/0x12f0 mm/vma.c:1380
 do_vmi_align_munmap+0x25d/0x420 mm/vma.c:1527
 do_vmi_munmap+0x253/0x2e0 mm/vma.c:1584
 __vm_munmap+0x23b/0x3d0 mm/vma.c:3155
 __do_sys_munmap mm/mmap.c:1080 [inline]
 __se_sys_munmap mm/mmap.c:1077 [inline]
 __x64_sys_munmap+0x60/0x70 mm/mmap.c:1077
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
page last free pid 7424 tgid 7422 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 __free_frozen_pages+0xbc4/0xd30 mm/page_alloc.c:2895
 __slab_free+0x303/0x3c0 mm/slub.c:4606
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x140 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:340
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4191 [inline]
 slab_alloc_node mm/slub.c:4240 [inline]
 kmem_cache_alloc_lru_noprof+0x1c6/0x3d0 mm/slub.c:4259
 fat_alloc_inode+0x2c/0xd0 fs/fat/inode.c:750
 alloc_inode+0x6a/0x1b0 fs/inode.c:346
 new_inode+0x22/0x170 fs/inode.c:1145
 fat_build_inode+0x202/0x3d0 fs/fat/inode.c:603
 vfat_create+0x16a/0x250 fs/fat/namei_vfat.c:773
 lookup_open fs/namei.c:3708 [inline]
 open_last_lookups fs/namei.c:3807 [inline]
 path_openat+0x14f4/0x3830 fs/namei.c:4043
 do_filp_open+0x1fa/0x410 fs/namei.c:4073
 do_sys_openat2+0x121/0x1c0 fs/open.c:1435
 do_sys_open fs/open.c:1450 [inline]
 __do_sys_openat fs/open.c:1466 [inline]
 __se_sys_openat fs/open.c:1461 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1461
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94

Memory state around the buggy address:
 ffff8880247b2d00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880247b2d80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880247b2e00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                     ^
 ffff8880247b2e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880247b2f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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