==================================================================
BUG: KASAN: use-after-free in kobject_get+0x113/0x120 lib/kobject.c:663
Read of size 1 at addr ffff88811251183c by task syz.4.418/1826

CPU: 1 PID: 1826 Comm: syz.4.418 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:88
 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:427 [inline]
 kasan_report+0x10f/0x150 mm/kasan/report.c:444
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report_generic.c:306
 kobject_get+0x113/0x120 lib/kobject.c:663
 get_device drivers/base/core.c:3518 [inline]
 device_add+0x2f0/0xe90 drivers/base/core.c:3342
 device_create_groups_vargs drivers/base/core.c:4118 [inline]
 device_create+0x26c/0x300 drivers/base/core.c:4160
 create_function_device+0x60/0x70 drivers/usb/gadget/configfs.c:31
 create_alsa_device drivers/usb/gadget/function/f_midi.c:1262 [inline]
 f_midi_alloc_inst+0x1a8/0x380 drivers/usb/gadget/function/f_midi.c:1303
 try_get_usb_function_instance drivers/usb/gadget/functions.c:28 [inline]
 usb_get_function_instance+0xe2/0x2f0 drivers/usb/gadget/functions.c:44
 function_make+0x118/0x350 drivers/usb/gadget/configfs.c:642
 configfs_mkdir+0x50a/0x9c0 fs/configfs/dir.c:1329
 vfs_mkdir+0x38b/0x590 fs/namei.c:4073
 do_mkdirat+0x174/0x4d0 fs/namei.c:4098
 __do_sys_mkdirat fs/namei.c:4113 [inline]
 __se_sys_mkdirat fs/namei.c:4111 [inline]
 __x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4111
 x64_sys_call+0x37e/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:259
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f66b70300d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f66b5a89028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f66b72b7fa0 RCX: 00007f66b70300d9
RDX: 00000000000001ff RSI: 0000200000000100 RDI: ffffffffffffff9c
RBP: 00007f66b70c7024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f66b72b8038 R14: 00007f66b72b7fa0 R15: 00007ffcc654a978
 </TASK>

Allocated by task 661:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:433 [inline]
 ____kasan_kmalloc mm/kasan/common.c:512 [inline]
 __kasan_kmalloc+0xd4/0x100 mm/kasan/common.c:521
 kasan_kmalloc include/linux/kasan.h:227 [inline]
 __kmalloc_track_caller+0x13c/0x2c0 mm/slub.c:4959
 kmalloc_reserve net/core/skbuff.c:357 [inline]
 __alloc_skb+0x210/0x730 net/core/skbuff.c:428
 alloc_skb include/linux/skbuff.h:1183 [inline]
 alloc_uevent_skb+0x85/0x240 lib/kobject_uevent.c:290
 uevent_net_broadcast_untagged lib/kobject_uevent.c:326 [inline]
 kobject_uevent_net_broadcast+0x335/0x5a0 lib/kobject_uevent.c:409
 kobject_uevent_env+0x52b/0x700 lib/kobject_uevent.c:608
 kobject_uevent+0x1d/0x30 lib/kobject_uevent.c:657
 __loop_clr_fd+0x906/0xd00 drivers/block/loop.c:1425
 lo_release+0x183/0x200 drivers/block/loop.c:2087
 blkdev_put+0x573/0x7a0 block/bdev.c:-1
 kill_block_super+0xb8/0xf0 fs/super.c:1430
 deactivate_locked_super+0xa0/0x100 fs/super.c:335
 deactivate_super+0xaf/0xe0 fs/super.c:366
 cleanup_mnt+0x44f/0x500 fs/namespace.c:1149
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1156
 task_work_run+0x127/0x190 kernel/task_work.c:188
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop+0xd0/0xe0 kernel/entry/common.c:181
 exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:307
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

Freed by task 101:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4a/0x70 mm/kasan/common.c:45
 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370
 ____kasan_slab_free+0x125/0x160 mm/kasan/common.c:365
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:373
 kasan_slab_free include/linux/kasan.h:193 [inline]
 slab_free_hook mm/slub.c:1728 [inline]
 slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1754
 slab_free mm/slub.c:3526 [inline]
 kfree+0xc4/0x270 mm/slub.c:4588
 skb_free_head net/core/skbuff.c:656 [inline]
 skb_release_data+0x7bd/0xa20 net/core/skbuff.c:678
 skb_release_all net/core/skbuff.c:743 [inline]
 __kfree_skb net/core/skbuff.c:757 [inline]
 consume_skb+0xab/0x1f0 net/core/skbuff.c:930
 skb_free_datagram+0x28/0xe0 net/core/datagram.c:325
 netlink_recvmsg+0x5dd/0xe40 net/netlink/af_netlink.c:2006
 ____sys_recvmsg+0x2ca/0x5b0 net/socket.c:-1
 ___sys_recvmsg+0x213/0x5c0 net/socket.c:2697
 __sys_recvmsg net/socket.c:2727 [inline]
 __do_sys_recvmsg net/socket.c:2737 [inline]
 __se_sys_recvmsg net/socket.c:2734 [inline]
 __x64_sys_recvmsg+0x1fe/0x2d0 net/socket.c:2734
 x64_sys_call+0x705/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:48
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

The buggy address belongs to the object at ffff888112511800
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 60 bytes inside of
 1024-byte region [ffff888112511800, ffff888112511c00)
The buggy address belongs to the page:
page:ffffea0004494400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x112510
head:ffffea0004494400 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head|zone=1)
raw: 4000000000010200 0000000000000000 0000000100000001 ffff888100043080
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 115, ts 6245929729, free_ts 0
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x192/0x1b0 mm/page_alloc.c:2607
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2613
 get_page_from_freelist+0x2c3a/0x2cd0 mm/page_alloc.c:4487
 __alloc_pages+0x1a2/0x460 mm/page_alloc.c:5824
 alloc_slab_page mm/slub.c:-1 [inline]
 allocate_slab mm/slub.c:1937 [inline]
 new_slab+0xa0/0x4d0 mm/slub.c:2000
 ___slab_alloc+0x3ac/0x840 mm/slub.c:3033
 __slab_alloc+0x49/0x90 mm/slub.c:3120
 slab_alloc_node mm/slub.c:3211 [inline]
 slab_alloc mm/slub.c:3255 [inline]
 __kmalloc_track_caller+0x169/0x2c0 mm/slub.c:4954
 kmalloc_reserve net/core/skbuff.c:357 [inline]
 __alloc_skb+0x210/0x730 net/core/skbuff.c:428
 alloc_skb include/linux/skbuff.h:1183 [inline]
 alloc_uevent_skb+0x85/0x240 lib/kobject_uevent.c:290
 uevent_net_broadcast_untagged lib/kobject_uevent.c:326 [inline]
 kobject_uevent_net_broadcast+0x335/0x5a0 lib/kobject_uevent.c:409
 kobject_uevent_env+0x52b/0x700 lib/kobject_uevent.c:608
 kobject_synth_uevent+0x457/0x940 lib/kobject_uevent.c:208
 uevent_store+0x25/0x60 drivers/base/core.c:2438
 dev_attr_store+0x5e/0x80 drivers/base/core.c:2136
 sysfs_kf_write+0x129/0x150 fs/sysfs/file.c:139
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888112511700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888112511780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888112511800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                        ^
 ffff888112511880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888112511900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
general protection fault, probably for non-canonical address 0xecedc82d0c67a9cd: 0000 [#1] PREEMPT SMP KASAN
KASAN: maybe wild-memory-access in range [0x676e6168633d4e68-0x676e6168633d4e6f]
CPU: 1 PID: 1826 Comm: syz.4.418 Tainted: G    B             syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:kobj_child_ns_ops lib/kobject.c:1084 [inline]
RIP: 0010:kobj_ns_ops lib/kobject.c:1092 [inline]
RIP: 0010:kobject_namespace lib/kobject.c:30 [inline]
RIP: 0010:create_dir lib/kobject.c:89 [inline]
RIP: 0010:kobject_add_internal+0x5e3/0xde0 lib/kobject.c:263
Code: 4c 89 e7 e8 6f 27 39 ff 4d 8b 24 24 4d 85 e4 0f 84 db 00 00 00 49 83 c4 20 4c 89 e0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 e7 e8 3f 27 39 ff 49 8b 04 24 48 85 c0 0f
RSP: 0018:ffffc90000c8f898 EFLAGS: 00010203
RAX: 0cedcc2d0c67a9cd RBX: ffff88810ed85a00 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff888112511828
RBP: ffffc90000c8f8f0 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000191f04 R12: 676e6168633d4e6f
R13: ffff88810ed85a18 R14: ffffffff86a49720 R15: ffff888112511800
FS:  00007f66b5a896c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f66b5a68d58 CR3: 0000000120e0a000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 kobject_add_varg lib/kobject.c:398 [inline]
 kobject_add+0x165/0x230 lib/kobject.c:450
 class_dir_create_and_add drivers/base/core.c:2976 [inline]
 get_device_parent+0x3a6/0x410 drivers/base/core.c:3031
 device_add+0x308/0xe90 drivers/base/core.c:3343
 device_create_groups_vargs drivers/base/core.c:4118 [inline]
 device_create+0x26c/0x300 drivers/base/core.c:4160
 create_function_device+0x60/0x70 drivers/usb/gadget/configfs.c:31
 create_alsa_device drivers/usb/gadget/function/f_midi.c:1262 [inline]
 f_midi_alloc_inst+0x1a8/0x380 drivers/usb/gadget/function/f_midi.c:1303
 try_get_usb_function_instance drivers/usb/gadget/functions.c:28 [inline]
 usb_get_function_instance+0xe2/0x2f0 drivers/usb/gadget/functions.c:44
 function_make+0x118/0x350 drivers/usb/gadget/configfs.c:642
 configfs_mkdir+0x50a/0x9c0 fs/configfs/dir.c:1329
 vfs_mkdir+0x38b/0x590 fs/namei.c:4073
 do_mkdirat+0x174/0x4d0 fs/namei.c:4098
 __do_sys_mkdirat fs/namei.c:4113 [inline]
 __se_sys_mkdirat fs/namei.c:4111 [inline]
 __x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4111
 x64_sys_call+0x37e/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:259
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f66b70300d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f66b5a89028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f66b72b7fa0 RCX: 00007f66b70300d9
RDX: 00000000000001ff RSI: 0000200000000100 RDI: ffffffffffffff9c
RBP: 00007f66b70c7024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f66b72b8038 R14: 00007f66b72b7fa0 R15: 00007ffcc654a978
 </TASK>
Modules linked in:
---[ end trace 263085ff4c175f78 ]---
RIP: 0010:kobj_child_ns_ops lib/kobject.c:1084 [inline]
RIP: 0010:kobj_ns_ops lib/kobject.c:1092 [inline]
RIP: 0010:kobject_namespace lib/kobject.c:30 [inline]
RIP: 0010:create_dir lib/kobject.c:89 [inline]
RIP: 0010:kobject_add_internal+0x5e3/0xde0 lib/kobject.c:263
Code: 4c 89 e7 e8 6f 27 39 ff 4d 8b 24 24 4d 85 e4 0f 84 db 00 00 00 49 83 c4 20 4c 89 e0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 e7 e8 3f 27 39 ff 49 8b 04 24 48 85 c0 0f
RSP: 0018:ffffc90000c8f898 EFLAGS: 00010203
RAX: 0cedcc2d0c67a9cd RBX: ffff88810ed85a00 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff888112511828
RBP: ffffc90000c8f8f0 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000191f04 R12: 676e6168633d4e6f
R13: ffff88810ed85a18 R14: ffffffff86a49720 R15: ffff888112511800
FS:  00007f66b5a896c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbc36606000 CR3: 0000000120e0a000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	4c 89 e7             	mov    %r12,%rdi
   3:	e8 6f 27 39 ff       	call   0xff392777
   8:	4d 8b 24 24          	mov    (%r12),%r12
   c:	4d 85 e4             	test   %r12,%r12
   f:	0f 84 db 00 00 00    	je     0xf0
  15:	49 83 c4 20          	add    $0x20,%r12
  19:	4c 89 e0             	mov    %r12,%rax
  1c:	48 c1 e8 03          	shr    $0x3,%rax
  20:	48 b9 00 00 00 00 00 	movabs $0xdffffc0000000000,%rcx
  27:	fc ff df
* 2a:	80 3c 08 00          	cmpb   $0x0,(%rax,%rcx,1) <-- trapping instruction
  2e:	74 08                	je     0x38
  30:	4c 89 e7             	mov    %r12,%rdi
  33:	e8 3f 27 39 ff       	call   0xff392777
  38:	49 8b 04 24          	mov    (%r12),%rax
  3c:	48 85 c0             	test   %rax,%rax
  3f:	0f                   	.byte 0xf