==================================================================
BUG: KASAN: slab-use-after-free in llc_conn_ac_send_sabme_cmd_p_set_x+0x38a/0x420 net/llc/llc_c_ac.c:782
Read of size 1 at addr ffff8880774e0010 by task syz.0.2215/12648

CPU: 0 UID: 0 PID: 12648 Comm: syz.0.2215 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <IRQ>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 llc_conn_ac_send_sabme_cmd_p_set_x+0x38a/0x420 net/llc/llc_c_ac.c:782
 llc_exec_conn_trans_actions net/llc/llc_conn.c:437 [inline]
 llc_conn_service net/llc/llc_conn.c:362 [inline]
 llc_conn_state_process+0x4fb/0x1380 net/llc/llc_conn.c:66
 llc_process_tmr_ev net/llc/llc_c_ac.c:1442 [inline]
 llc_conn_tmr_common_cb+0x34a/0x780 net/llc/llc_c_ac.c:1325
 call_timer_fn+0x18d/0x5f0 kernel/time/timer.c:1748
 expire_timers kernel/time/timer.c:1799 [inline]
 __run_timers kernel/time/timer.c:2374 [inline]
 __run_timer_base+0x652/0x8b0 kernel/time/timer.c:2386
 run_timer_base kernel/time/timer.c:2395 [inline]
 run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2405
 handle_softirqs+0x226/0x860 kernel/softirq.c:645
 __do_softirq kernel/softirq.c:679 [inline]
 invoke_softirq kernel/softirq.c:519 [inline]
 __irq_exit_rcu+0xcb/0x220 kernel/softirq.c:758
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:775
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1062
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:unwind_get_return_address+0x56/0x90 arch/x86/kernel/unwind_orc.c:385
Code: 83 c3 48 49 89 df 49 c1 ef 03 43 80 3c 37 00 74 08 48 89 df e8 cb 0d c0 00 48 8b 3b e8 93 db 18 00 85 c0 74 14 43 80 3c 37 00 <74> 08 48 89 df e8 b0 0d c0 00 48 8b 03 eb 02 31 c0 5b 41 5e 41 5f
RSP: 0018:ffffc90010326dc8 EFLAGS: 00000246
RAX: 0000000000000001 RBX: ffffc90010326e30 RCX: 0000000000000000
RDX: ffffc90010326e01 RSI: ffffffff8e703762 RDI: ffffffff821af0ce
RBP: ffffc90010326e70 R08: ffffc90010327c30 R09: 0000000000000000
R10: ffffc90010326e38 R11: fffff52002064dc9 R12: ffff888030c91f40
R13: 1ffff110061924a7 R14: dffffc0000000000 R15: 1ffff92002064dc6
 arch_stack_walk+0xfb/0x150 arch/x86/kernel/stacktrace.c:26
 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
 save_stack+0x122/0x230 mm/page_owner.c:183
 __set_page_owner+0x8d/0x4c0 mm/page_owner.c:359
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1853
 prep_new_page mm/page_alloc.c:1861 [inline]
 get_page_from_freelist+0x2209/0x2280 mm/page_alloc.c:3925
 __alloc_frozen_pages_noprof+0x217/0x5a0 mm/page_alloc.c:5418
 alloc_pages_mpol+0x21e/0x390 mm/mempolicy.c:2507
 folio_alloc_mpol_noprof+0x39/0x160 mm/mempolicy.c:2526
 shmem_alloc_folio mm/shmem.c:2135 [inline]
 shmem_alloc_and_add_folio+0x43e/0xf60 mm/shmem.c:2177
 shmem_get_folio_gfp+0x594/0x1330 mm/shmem.c:2730
 shmem_fault+0x179/0x390 mm/shmem.c:2924
 __do_fault+0x138/0x2a0 mm/memory.c:5534
 do_read_fault mm/memory.c:5969 [inline]
 do_fault mm/memory.c:6103 [inline]
 do_pte_missing+0x2215/0x34b0 mm/memory.c:4663
 handle_pte_fault mm/memory.c:6527 [inline]
 __handle_mm_fault mm/memory.c:6676 [inline]
 handle_mm_fault+0x1a53/0x3750 mm/memory.c:6843
 faultin_page mm/gup.c:1126 [inline]
 __get_user_pages+0x1670/0x2750 mm/gup.c:1428
 populate_vma_page_range+0x2be/0x3c0 mm/gup.c:1860
 __mm_populate+0x25f/0x390 mm/gup.c:1963
 mm_populate include/linux/mm.h:4269 [inline]
 vm_mmap_pgoff+0x353/0x4e0 mm/util.c:586
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2f2e99e159
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:00007f2f2f928028 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f2f2ec25fa0 RCX: 00007f2f2e99e159
RDX: b635773f06ebbeee RSI: 0000000000b36000 RDI: 0000200000000000
RBP: 00007f2f2ea35024 R08: ffffffffffffffff R09: 0000000000004000
R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2f2ec26038 R14: 00007f2f2ec25fa0 R15: 00007ffd6655c4d8
 </TASK>

Allocated by task 12643:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x31c/0x600 mm/slub.c:5568
 _kmalloc_noprof include/linux/slab.h:991 [inline]
 _kzalloc_noprof include/linux/slab.h:1312 [inline]
 llc_sap_alloc net/llc/llc_core.c:29 [inline]
 llc_sap_open+0xe1/0x3b0 net/llc/llc_core.c:96
 llc_ui_autobind+0x1f1/0x560 net/llc/af_llc.c:301
 llc_ui_connect+0x1dc/0xe40 net/llc/af_llc.c:498
 connect_socket net/socket.c:2141 [inline]
 __sys_connect_file net/socket.c:2166 [inline]
 __sys_connect+0x316/0x450 net/socket.c:2183
 __do_sys_connect net/socket.c:2189 [inline]
 __se_sys_connect net/socket.c:2186 [inline]
 __x64_sys_connect+0x7a/0x90 net/socket.c:2186
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 0:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2748 [inline]
 __rcu_free_sheaf_prepare+0x12d/0x2a0 mm/slub.c:3009
 rcu_free_sheaf+0x31/0x200 mm/slub.c:6057
 rcu_do_batch kernel/rcu/tree.c:2650 [inline]
 rcu_core+0x926/0x1260 kernel/rcu/tree.c:2919
 handle_softirqs+0x226/0x860 kernel/softirq.c:645
 __do_softirq kernel/softirq.c:679 [inline]
 invoke_softirq kernel/softirq.c:519 [inline]
 __irq_exit_rcu+0xcb/0x220 kernel/softirq.c:758
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:775
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1062
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674

The buggy address belongs to the object at ffff8880774e0000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 16 bytes inside of
 freed 2048-byte region [ffff8880774e0000, ffff8880774e0800)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x774e0
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801b042000 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801b042000 dead000000000100 dead000000000122
head: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000
head: 00fff00000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
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 25, tgid 25 (kworker/1:0), ts 88714884177
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1853
 prep_new_page mm/page_alloc.c:1861 [inline]
 get_page_from_freelist+0x2209/0x2280 mm/page_alloc.c:3925
 __alloc_frozen_pages_noprof+0x217/0x5a0 mm/page_alloc.c:5418
 alloc_slab_page mm/slub.c:3347 [inline]
 allocate_slab+0x7d/0x620 mm/slub.c:3462
 new_slab mm/slub.c:3513 [inline]
 refill_objects+0x2d5/0x350 mm/slub.c:7416
 refill_sheaf mm/slub.c:2885 [inline]
 __pcs_replace_empty_main+0x2c8/0x6c0 mm/slub.c:4774
 alloc_from_pcs mm/slub.c:4850 [inline]
 slab_alloc_node mm/slub.c:4984 [inline]
 __do_kmalloc_node mm/slub.c:5418 [inline]
 __kmalloc_node_track_caller_noprof+0x543/0x720 mm/slub.c:5550
 kmalloc_reserve net/core/skbuff.c:637 [inline]
 __alloc_skb+0x2c1/0x7a0 net/core/skbuff.c:715
 alloc_skb include/linux/skbuff.h:1384 [inline]
 mld_newpack+0x165/0xcb0 net/ipv6/mcast.c:1810
 add_grhead net/ipv6/mcast.c:1921 [inline]
 add_grec+0x119f/0x19d0 net/ipv6/mcast.c:2060
 mld_send_cr net/ipv6/mcast.c:2185 [inline]
 mld_ifc_work+0x6f1/0xd60 net/ipv6/mcast.c:2739
 process_one_work kernel/workqueue.c:3399 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3482
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3563
 kthread+0x38b/0x480 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
page last free pid 1225 tgid 1225 ts 88613556522 stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 __free_pages_prepare mm/page_alloc.c:1400 [inline]
 __free_frozen_pages+0xc93/0xd90 mm/page_alloc.c:2944
 __slab_free+0x274/0x2c0 mm/slub.c:5820
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4683 [inline]
 slab_alloc_node mm/slub.c:4996 [inline]
 __kmalloc_cache_noprof+0x29a/0x600 mm/slub.c:5564
 _kmalloc_noprof include/linux/slab.h:991 [inline]
 _kzalloc_noprof include/linux/slab.h:1312 [inline]
 nsim_fib6_rt_create drivers/net/netdevsim/fib.c:547 [inline]
 nsim_fib6_rt_insert drivers/net/netdevsim/fib.c:752 [inline]
 nsim_fib6_event drivers/net/netdevsim/fib.c:856 [inline]
 nsim_fib_event+0xf37/0xa3a0 drivers/net/netdevsim/fib.c:889
 nsim_fib_event_work+0x244/0x3b0 drivers/net/netdevsim/fib.c:1493
 process_one_work kernel/workqueue.c:3399 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3482
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3563
 kthread+0x38b/0x480 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff8880774dff00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880774dff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880774e0000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff8880774e0080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880774e0100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
   0:	83 c3 48             	add    $0x48,%ebx
   3:	49 89 df             	mov    %rbx,%r15
   6:	49 c1 ef 03          	shr    $0x3,%r15
   a:	43 80 3c 37 00       	cmpb   $0x0,(%r15,%r14,1)
   f:	74 08                	je     0x19
  11:	48 89 df             	mov    %rbx,%rdi
  14:	e8 cb 0d c0 00       	call   0xc00de4
  19:	48 8b 3b             	mov    (%rbx),%rdi
  1c:	e8 93 db 18 00       	call   0x18dbb4
  21:	85 c0                	test   %eax,%eax
  23:	74 14                	je     0x39
  25:	43 80 3c 37 00       	cmpb   $0x0,(%r15,%r14,1)
* 2a:	74 08                	je     0x34 <-- trapping instruction
  2c:	48 89 df             	mov    %rbx,%rdi
  2f:	e8 b0 0d c0 00       	call   0xc00de4
  34:	48 8b 03             	mov    (%rbx),%rax
  37:	eb 02                	jmp    0x3b
  39:	31 c0                	xor    %eax,%eax
  3b:	5b                   	pop    %rbx
  3c:	41 5e                	pop    %r14
  3e:	41 5f                	pop    %r15