==================================================================
BUG: KASAN: use-after-free in llc_conn_ac_send_sabme_cmd_p_set_x+0x332/0x3c0 net/llc/llc_c_ac.c:788
Read of size 1 at addr ffff888147de3010 by task kworker/0:3/4176

CPU: 0 PID: 4176 Comm: kworker/0:3 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: ipv6_addrconf addrconf_dad_work
Call Trace:
 <IRQ>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 llc_conn_ac_send_sabme_cmd_p_set_x+0x332/0x3c0 net/llc/llc_c_ac.c:788
 llc_exec_conn_trans_actions net/llc/llc_conn.c:442 [inline]
 llc_conn_service net/llc/llc_conn.c:367 [inline]
 llc_conn_state_process+0x506/0x12b0 net/llc/llc_conn.c:71
 llc_process_tmr_ev net/llc/llc_c_ac.c:1445 [inline]
 llc_conn_tmr_common_cb+0x336/0x7e0 net/llc/llc_c_ac.c:1331
 call_timer_fn+0x17b/0x540 kernel/time/timer.c:1648
 expire_timers kernel/time/timer.c:1699 [inline]
 __run_timers+0x56c/0x810 kernel/time/timer.c:1970
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1983
 handle_softirqs+0x336/0x830 kernel/softirq.c:576
 do_softirq+0x142/0x210 kernel/softirq.c:477
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0x180/0x1c0 kernel/softirq.c:401
 rcu_read_unlock_bh include/linux/rcupdate.h:810 [inline]
 ip6_finish_output2+0x111c/0x1530 net/ipv6/ip6_output.c:131
 dst_output include/net/dst.h:452 [inline]
 NF_HOOK include/linux/netfilter.h:302 [inline]
 ndisc_send_skb+0xb7a/0x1410 net/ipv6/ndisc.c:513
 addrconf_dad_completed+0x75f/0xc80 net/ipv6/addrconf.c:4285
 addrconf_dad_work+0xc83/0x1530 net/ipv6/addrconf.c:-1
 process_one_work+0x867/0xff0 kernel/workqueue.c:2310
 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Allocated by task 4288:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 ____kasan_kmalloc mm/kasan/common.c:513 [inline]
 __kasan_kmalloc+0xaf/0xe0 mm/kasan/common.c:522
 kmalloc include/linux/slab.h:607 [inline]
 kzalloc include/linux/slab.h:738 [inline]
 llc_sap_alloc net/llc/llc_core.c:35 [inline]
 llc_sap_open+0xda/0x330 net/llc/llc_core.c:102
 llc_ui_autobind+0x1fa/0x4b0 net/llc/af_llc.c:306
 llc_ui_connect+0x1c5/0xc70 net/llc/af_llc.c:501
 __sys_connect_file net/socket.c:1933 [inline]
 __sys_connect+0x3cb/0x450 net/socket.c:1950
 __do_sys_connect net/socket.c:1960 [inline]
 __se_sys_connect net/socket.c:1957 [inline]
 __x64_sys_connect+0x76/0x80 net/socket.c:1957
 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

Freed by task 4200:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:46
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
 ____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1710 [inline]
 slab_free_freelist_hook+0xec/0x170 mm/slub.c:1736
 slab_free mm/slub.c:3504 [inline]
 kmem_cache_free_bulk+0x38b/0x490 mm/slub.c:3645
 kfree_bulk include/linux/slab.h:465 [inline]
 kfree_rcu_work+0x311/0x900 kernel/rcu/tree.c:3299
 process_one_work+0x867/0xff0 kernel/workqueue.c:2310
 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

Last potentially related work creation:
 kasan_save_stack+0x35/0x60 mm/kasan/common.c:38
 kasan_record_aux_stack+0xb8/0x100 mm/kasan/generic.c:348
 kvfree_call_rcu+0x105/0x7f0 kernel/rcu/tree.c:3600
 llc_sap_put include/net/llc.h:132 [inline]
 llc_ui_release+0x212/0x450 net/llc/af_llc.c:223
 __sock_release net/socket.c:651 [inline]
 sock_close+0xbf/0x210 net/socket.c:1346
 __fput+0x212/0x8c0 fs/file_table.c:311
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 get_signal+0x123e/0x12e0 kernel/signal.c:2681
 arch_do_signal_or_restart+0xe6/0x12a0 arch/x86/kernel/signal.c:867
 handle_signal_work kernel/entry/common.c:154 [inline]
 exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

The buggy address belongs to the object at ffff888147de3000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 16 bytes inside of
 2048-byte region [ffff888147de3000, ffff888147de3800)
The buggy address belongs to the page:
page:ffffea00051f7800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x147de0
head:ffffea00051f7800 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x57ff00000010200(slab|head|node=1|zone=2|lastcpupid=0x7ff)
raw: 057ff00000010200 dead000000000100 dead000000000122 ffff888016c42000
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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, ts 6798784437, free_ts 0
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x24f6/0x2670 mm/page_alloc.c:4192
 __alloc_pages+0x1ee/0x480 mm/page_alloc.c:5501
 alloc_page_interleave+0x24/0x1e0 mm/mempolicy.c:2031
 alloc_slab_page mm/slub.c:1780 [inline]
 allocate_slab mm/slub.c:1917 [inline]
 new_slab+0xc0/0x4b0 mm/slub.c:1980
 ___slab_alloc+0x807/0xdd0 mm/slub.c:3013
 __slab_alloc mm/slub.c:3100 [inline]
 slab_alloc_node mm/slub.c:3191 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 kmem_cache_alloc_trace+0xf9/0x290 mm/slub.c:3250
 kmalloc include/linux/slab.h:607 [inline]
 kzalloc include/linux/slab.h:738 [inline]
 device_create_groups_vargs drivers/base/core.c:4105 [inline]
 device_create+0x13a/0x300 drivers/base/core.c:4165
 bdi_register_va+0x93/0x6c0 mm/backing-dev.c:885
 bdi_register+0xdf/0x130 mm/backing-dev.c:917
 device_add_disk+0x7f1/0xd00 block/genhd.c:502
 add_disk include/linux/genhd.h:200 [inline]
 nbd_dev_add+0x762/0xb20 drivers/block/nbd.c:1786
 nbd_init+0x21c/0x2c0 drivers/block/nbd.c:2500
 do_one_initcall+0x272/0x730 init/main.c:1315
 do_initcall_level+0x13d/0x1f0 init/main.c:1388
 do_initcalls+0x4b/0x90 init/main.c:1404
 kernel_init_freeable+0x3d5/0x560 init/main.c:1628
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888147de2f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888147de2f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888147de3000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff888147de3080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888147de3100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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