================================================================== BUG: KASAN: slab-use-after-free in sysfs_remove_file_ns+0x3d/0x70 fs/sysfs/file.c:522 Read of size 8 at addr ffff888053ae9630 by task syz.0.9910/4199 CPU: 0 UID: 0 PID: 4199 Comm: syz.0.9910 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 Call Trace: 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 do_devconfig_ioctl drivers/comedi/comedi_fops.c:848 [inline] comedi_unlocked_ioctl+0xcde/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: 0033:0x7efd9638eec9 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:00007efd97282038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007efd965e6180 RCX: 00007efd9638eec9 RDX: 0000000000000000 RSI: 0000000040946400 RDI: 0000000000000008 RBP: 00007efd96411f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007efd965e6218 R14: 00007efd965e6180 R15: 00007ffcbb343f88 Allocated by task 14912: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:388 [inline] __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:405 kasan_kmalloc include/linux/kasan.h:260 [inline] __kmalloc_cache_noprof+0x230/0x3d0 mm/slub.c:4407 kmalloc_noprof include/linux/slab.h:905 [inline] kzalloc_noprof include/linux/slab.h:1039 [inline] bus_add_driver+0x162/0x640 drivers/base/bus.c:662 driver_register+0x23a/0x320 drivers/base/driver.c:249 c6xdigio_attach+0x94/0x890 drivers/comedi/drivers/c6xdigio.c:253 comedi_device_attach+0x51f/0x720 drivers/comedi/drivers.c:1007 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 Freed by task 4024: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576 poison_slab_object mm/kasan/common.c:243 [inline] __kasan_slab_free+0x5b/0x80 mm/kasan/common.c:275 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2422 [inline] slab_free mm/slub.c:4695 [inline] kfree+0x18e/0x440 mm/slub.c:4894 kobject_cleanup lib/kobject.c:689 [inline] kobject_release lib/kobject.c:720 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x22b/0x480 lib/kobject.c:737 bus_remove_driver+0x245/0x2f0 drivers/base/bus.c:749 comedi_device_detach_locked+0x178/0x750 drivers/comedi/drivers.c:207 do_devconfig_ioctl drivers/comedi/comedi_fops.c:848 [inline] comedi_unlocked_ioctl+0xcde/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 The buggy address belongs to the object at ffff888053ae9600 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 48 bytes inside of freed 256-byte region [ffff888053ae9600, ffff888053ae9700) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888053ae9800 pfn:0x53ae8 head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0xfff00000000240(workingset|head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000240 ffff88801a441b40 ffffea0001e05190 ffffea0000acca10 raw: ffff888053ae9800 0000000000100009 00000000f5000000 0000000000000000 head: 00fff00000000240 ffff88801a441b40 ffffea0001e05190 ffffea0000acca10 head: ffff888053ae9800 0000000000100009 00000000f5000000 0000000000000000 head: 00fff00000000001 ffffea00014eba01 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 14337, tgid 14335 (syz.9.2843), ts 420304912875, free_ts 395147751730 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] __do_kmalloc_node mm/slub.c:4375 [inline] __kmalloc_noprof+0x305/0x4f0 mm/slub.c:4388 kmalloc_noprof include/linux/slab.h:909 [inline] io_cache_alloc_new+0x40/0x100 io_uring/alloc_cache.c:40 io_cache_alloc io_uring/alloc_cache.h:59 [inline] io_uring_alloc_async_data io_uring/io_uring.h:246 [inline] io_rw_alloc_async io_uring/rw.c:202 [inline] __io_prep_rw+0x23f/0xe20 io_uring/rw.c:261 io_prep_rw io_uring/rw.c:320 [inline] io_prep_rwv+0x8c/0x3d0 io_uring/rw.c:342 io_init_req io_uring/io_uring.c:2197 [inline] io_submit_sqe io_uring/io_uring.c:2244 [inline] io_submit_sqes+0x917/0x1d30 io_uring/io_uring.c:2396 __do_sys_io_uring_enter io_uring/io_uring.c:3463 [inline] __se_sys_io_uring_enter+0x2df/0x2b20 io_uring/io_uring.c:3397 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 page last free pid 5859 tgid 5859 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 discard_slab mm/slub.c:2758 [inline] __put_partials+0x156/0x1a0 mm/slub.c:3223 put_cpu_partial+0x17c/0x250 mm/slub.c:3298 __slab_free+0x2d5/0x3c0 mm/slub.c:4565 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_noprof+0x1c1/0x3c0 mm/slub.c:4247 getname_flags+0xb8/0x540 fs/namei.c:146 user_path_at+0x24/0x60 fs/namei.c:3126 ksys_umount fs/namespace.c:2112 [inline] __do_sys_umount fs/namespace.c:2120 [inline] __se_sys_umount fs/namespace.c:2118 [inline] __x64_sys_umount+0xee/0x160 fs/namespace.c:2118 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 Memory state around the buggy address: ffff888053ae9500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888053ae9580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888053ae9600: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888053ae9680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888053ae9700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================