Good day, dear maintainers,

We found a bug using a modified kernel configuration file used by syzbot.

We enhanced the probability of vulnerability discovery using our prototype
system developed based on syzkaller and found a bug "' KASAN:
slab-use-after-free Read in nfc_llcp_unregister_device." I'm still working
on it to find out its root cause and availability.

The following are details:

Kernel Branch: 6.4.0-rc3

Kernel Config and Reproducer are attached.
Thank you!

Best regards,
Ren Zezhong

Syzkaller hit 'KASAN: slab-use-after-free Read in
nfc_llcp_unregister_device' bug.

==================================================================
BUG: KASAN: slab-use-after-free in __list_del_entry_valid+0x170/0x1b0
lib/list_debug.c:62
Read of size 8 at addr ffff88801a961008 by task syz-executor.6/106718

CPU: 1 PID: 106718 Comm: syz-executor.6 Not tainted 6.4.0-rc3 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd5/0x150 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:351 [inline]
 print_report+0xc1/0x5e0 mm/kasan/report.c:462
 kasan_report+0xbc/0xf0 mm/kasan/report.c:572
 __list_del_entry_valid+0x170/0x1b0 lib/list_debug.c:62
 __list_del_entry include/linux/list.h:134 [inline]
 list_del include/linux/list.h:148 [inline]
 local_release net/nfc/llcp_core.c:172 [inline]
 kref_put include/linux/kref.h:65 [inline]
 nfc_llcp_local_put net/nfc/llcp_core.c:182 [inline]
 nfc_llcp_local_put net/nfc/llcp_core.c:177 [inline]
 nfc_llcp_unregister_device+0xb4/0x260 net/nfc/llcp_core.c:1620
 nfc_unregister_device+0x192/0x330 net/nfc/core.c:1179
 virtual_ncidev_close+0x4e/0xa0 drivers/nfc/virtual_ncidev.c:163
 __fput+0x27c/0xa90 fs/file_table.c:321
 task_work_run+0x164/0x250 kernel/task_work.c:179
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
 exit_to_user_mode_prepare+0x210/0x240 kernel/entry/common.c:204
 __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline]
 syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:297
 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f0a78e8dbcb
Code: 03 00 00 00 0f 05 48 3d 00 f0 ff ff 77 41 c3 48 83 ec 18 89 7c
24 0c e8 53 fc 02 00 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d
00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 a1 fc 02 00 8b 44
RSP: 002b:00007ffce2ce4790 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000005 RCX: 00007f0a78e8dbcb
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000004
RBP: 00007f0a78fcd980 R08: 0000000000000000 R09: 00007f0a78a00b40
R10: 0000000000000000 R11: 0000000000000293 R12: 00000000001445e6
R13: 00007ffce2ce4890 R14: 00007f0a78a00f68 R15: 00007f0a78a00f60
 </TASK>

Allocated by task 106708:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:45
 kasan_set_track+0x21/0x30 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:374 [inline]
 ____kasan_kmalloc mm/kasan/common.c:333 [inline]
 __kasan_kmalloc+0x9e/0xa0 mm/kasan/common.c:383
 kmalloc include/linux/slab.h:559 [inline]
 kzalloc include/linux/slab.h:680 [inline]
 nfc_llcp_register_device+0x45/0x9e0 net/nfc/llcp_core.c:1567
 nfc_register_device+0x6c/0x3c0 net/nfc/core.c:1124
 nci_register_device+0x7c7/0xb50 net/nfc/nci/core.c:1257
 virtual_ncidev_open+0x14b/0x220 drivers/nfc/virtual_ncidev.c:148
 misc_open+0x379/0x490 drivers/char/misc.c:165
 chrdev_open+0x266/0x770 fs/char_dev.c:414
 do_dentry_open+0x67f/0x13c0 fs/open.c:920
 do_open fs/namei.c:3636 [inline]
 path_openat+0x1b99/0x26c0 fs/namei.c:3791
 do_filp_open+0x1c5/0x410 fs/namei.c:3818
 do_sys_openat2+0x16d/0x4c0 fs/open.c:1356
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x13c/0x1f0 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 106706:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:45
 kasan_set_track+0x21/0x30 mm/kasan/common.c:52
 kasan_save_free_info+0x2a/0x40 mm/kasan/generic.c:521
 ____kasan_slab_free mm/kasan/common.c:236 [inline]
 ____kasan_slab_free+0x161/0x1c0 mm/kasan/common.c:200
 kasan_slab_free include/linux/kasan.h:162 [inline]
 slab_free_hook mm/slub.c:1781 [inline]
 slab_free_freelist_hook+0x89/0x1c0 mm/slub.c:1807
 slab_free mm/slub.c:3786 [inline]
 __kmem_cache_free+0xab/0x2e0 mm/slub.c:3799
 local_release net/nfc/llcp_core.c:174 [inline]
 kref_put include/linux/kref.h:65 [inline]
 nfc_llcp_local_put net/nfc/llcp_core.c:182 [inline]
 nfc_llcp_local_put net/nfc/llcp_core.c:177 [inline]
 nfc_llcp_unregister_device+0x1b6/0x260 net/nfc/llcp_core.c:1620
 nfc_unregister_device+0x192/0x330 net/nfc/core.c:1179
 virtual_ncidev_close+0x4e/0xa0 drivers/nfc/virtual_ncidev.c:163
 __fput+0x27c/0xa90 fs/file_table.c:321
 task_work_run+0x164/0x250 kernel/task_work.c:179
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
 exit_to_user_mode_prepare+0x210/0x240 kernel/entry/common.c:204
 __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline]
 syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:297
 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Last potentially related work creation:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:45
 __kasan_record_aux_stack+0xbf/0xd0 mm/kasan/generic.c:491
 insert_work+0x48/0x360 kernel/workqueue.c:1365
 __queue_work+0x5c6/0xfb0 kernel/workqueue.c:1526
 queue_work_on+0xee/0x110 kernel/workqueue.c:1554
 queue_work include/linux/workqueue.h:505 [inline]
 schedule_work include/linux/workqueue.h:566 [inline]
 rfkill_register+0x678/0xb00 net/rfkill/core.c:1090
 nfc_register_device+0x120/0x3c0 net/nfc/core.c:1132
 nci_register_device+0x7c7/0xb50 net/nfc/nci/core.c:1257
 virtual_ncidev_open+0x14b/0x220 drivers/nfc/virtual_ncidev.c:148
 misc_open+0x379/0x490 drivers/char/misc.c:165
 chrdev_open+0x266/0x770 fs/char_dev.c:414
 do_dentry_open+0x67f/0x13c0 fs/open.c:920
 do_open fs/namei.c:3636 [inline]
 path_openat+0x1b99/0x26c0 fs/namei.c:3791
 do_filp_open+0x1c5/0x410 fs/namei.c:3818
 do_sys_openat2+0x16d/0x4c0 fs/open.c:1356
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x13c/0x1f0 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Second to last potentially related work creation:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:45
 __kasan_record_aux_stack+0xbf/0xd0 mm/kasan/generic.c:491
 insert_work+0x48/0x360 kernel/workqueue.c:1365
 __queue_work+0x5c6/0xfb0 kernel/workqueue.c:1526
 queue_work_on+0xee/0x110 kernel/workqueue.c:1554
 queue_work include/linux/workqueue.h:505 [inline]
 schedule_work include/linux/workqueue.h:566 [inline]
 rfkill_register+0x678/0xb00 net/rfkill/core.c:1090
 nfc_register_device+0x120/0x3c0 net/nfc/core.c:1132
 nci_register_device+0x7c7/0xb50 net/nfc/nci/core.c:1257
 virtual_ncidev_open+0x14b/0x220 drivers/nfc/virtual_ncidev.c:148
 misc_open+0x379/0x490 drivers/char/misc.c:165
 chrdev_open+0x266/0x770 fs/char_dev.c:414
 do_dentry_open+0x67f/0x13c0 fs/open.c:920
 do_open fs/namei.c:3636 [inline]
 path_openat+0x1b99/0x26c0 fs/namei.c:3791
 do_filp_open+0x1c5/0x410 fs/namei.c:3818
 do_sys_openat2+0x16d/0x4c0 fs/open.c:1356
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x13c/0x1f0 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff88801a961000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 8 bytes inside of
 freed 2048-byte region [ffff88801a961000, ffff88801a961800)

The buggy address belongs to the physical page:
page:ffffea00006a5800 refcount:1 mapcount:0 mapping:0000000000000000
index:0x0 pfn:0x1a960
head:ffffea00006a5800 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000010200 ffff888012442000 0000000000000000 dead000000000001
raw: 0000000000000000 0000000000080008 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
0xd28c0(GFP_NOWAIT|__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC),
pid 9047, tgid 9047 (kworker/1:2), ts 1085728553252, free_ts
1084588319734
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x2d7/0x350 mm/page_alloc.c:1731
 prep_new_page mm/page_alloc.c:1738 [inline]
 get_page_from_freelist+0xf60/0x2ac0 mm/page_alloc.c:3502
 __alloc_pages+0x1c7/0x490 mm/page_alloc.c:4768
 alloc_pages+0x1a6/0x270 mm/mempolicy.c:2279
 alloc_slab_page mm/slub.c:1851 [inline]
 allocate_slab+0x25f/0x390 mm/slub.c:1998
 new_slab mm/slub.c:2051 [inline]
 ___slab_alloc+0xa99/0x13e0 mm/slub.c:3192
 __slab_alloc.constprop.0+0x56/0xa0 mm/slub.c:3291
 __slab_alloc_node mm/slub.c:3344 [inline]
 slab_alloc_node mm/slub.c:3441 [inline]
 __kmem_cache_alloc_node+0x12e/0x320 mm/slub.c:3490
 __do_kmalloc_node mm/slab_common.c:965 [inline]
 __kmalloc_node_track_caller+0x4b/0x190 mm/slab_common.c:986
 kmalloc_reserve+0xf0/0x270 net/core/skbuff.c:585
 pskb_expand_head+0x233/0x10e0 net/core/skbuff.c:2054
 netlink_trim+0x1ea/0x240 net/netlink/af_netlink.c:1321
 netlink_broadcast+0x5f/0xd90 net/netlink/af_netlink.c:1517
 nlmsg_multicast include/net/netlink.h:1083 [inline]
 nlmsg_notify+0x8f/0x280 net/netlink/af_netlink.c:2589
 rtnl_notify net/core/rtnetlink.c:771 [inline]
 rtmsg_ifinfo_send net/core/rtnetlink.c:4016 [inline]
 rtmsg_ifinfo_event net/core/rtnetlink.c:4032 [inline]
 rtmsg_ifinfo_event net/core/rtnetlink.c:4019 [inline]
 rtmsg_ifinfo+0x16a/0x1a0 net/core/rtnetlink.c:4038
 netdev_state_change net/core/dev.c:1319 [inline]
 netdev_state_change+0x127/0x140 net/core/dev.c:1310
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1302 [inline]
 free_unref_page_prepare+0x4dd/0xb80 mm/page_alloc.c:2564
 free_unref_page+0x2f/0x3c0 mm/page_alloc.c:2659
 qlink_free mm/kasan/quarantine.c:166 [inline]
 qlist_free_all+0x6a/0x170 mm/kasan/quarantine.c:185
 kasan_quarantine_reduce+0x187/0x1d0 mm/kasan/quarantine.c:292
 __kasan_slab_alloc+0x5f/0x80 mm/kasan/common.c:305
 kasan_slab_alloc include/linux/kasan.h:186 [inline]
 slab_post_alloc_hook mm/slab.h:711 [inline]
 slab_alloc_node mm/slub.c:3451 [inline]
 __kmem_cache_alloc_node+0x174/0x320 mm/slub.c:3490
 __do_kmalloc_node mm/slab_common.c:965 [inline]
 __kmalloc_node+0x4d/0x190 mm/slab_common.c:973
 kmalloc_node include/linux/slab.h:579 [inline]
 kvmalloc_node+0x9e/0x1a0 mm/util.c:604
 kvmalloc include/linux/slab.h:697 [inline]
 seq_buf_alloc fs/seq_file.c:38 [inline]
 seq_read_iter+0x7f8/0x1260 fs/seq_file.c:210
 kernfs_fop_read_iter+0x4c7/0x690 fs/kernfs/file.c:279
 call_read_iter include/linux/fs.h:1862 [inline]
 new_sync_read fs/read_write.c:389 [inline]
 vfs_read+0x4ab/0x8a0 fs/read_write.c:470
 ksys_read+0x127/0x250 fs/read_write.c:613
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:
 ffff88801a960f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88801a960f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88801a961000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff88801a961080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88801a961100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================