==================================================================
BUG: KASAN: slab-use-after-free in llc_conn_ac_send_sabme_cmd_p_set_x+0x442/0x470 net/llc/llc_c_ac.c:782
Read of size 1 at addr ffff88802b618010 by task syz.5.1812/14154
CPU: 0 UID: 0 PID: 14154 Comm: syz.5.1812 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Call Trace:
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0x13d/0x4b0 mm/kasan/report.c:482
kasan_report+0xdf/0x1c0 mm/kasan/report.c:595
llc_conn_ac_send_sabme_cmd_p_set_x+0x442/0x470 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+0x3ec/0x1480 net/llc/llc_conn.c:66
llc_process_tmr_ev net/llc/llc_c_ac.c:1442 [inline]
llc_conn_tmr_common_cb+0x2d4/0x880 net/llc/llc_c_ac.c:1325
call_timer_fn+0x19a/0x610 kernel/time/timer.c:1748
expire_timers kernel/time/timer.c:1799 [inline]
__run_timers+0x757/0xb00 kernel/time/timer.c:2374
__run_timer_base kernel/time/timer.c:2386 [inline]
__run_timer_base kernel/time/timer.c:2378 [inline]
run_timer_base+0x114/0x190 kernel/time/timer.c:2395
run_timer_softirq+0x1a/0x50 kernel/time/timer.c:2405
handle_softirqs+0x1ea/0x9b0 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0x162/0x210 kernel/softirq.c:735
irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
sysvec_apic_timer_interrupt+0xa3/0xc0 arch/x86/kernel/apic/apic.c:1062
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:188 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x29/0x50 kernel/locking/spinlock.c:206
Code: 90 f3 0f 1e fa 53 48 8b 74 24 08 48 89 fb 48 83 c7 18 e8 3a e2 24 f6 48 89 df e8 c2 31 25 f6 e8 5d 9b 51 f6 fb bf 01 00 00 00 72 3f 14 f6 65 8b 05 db 76 c3 08 85 c0 74 06 5b e9 81 4b 00 00
RSP: 0018:ffffc90003816a60 EFLAGS: 00000202
RAX: 000000000001407f RBX: ffff88802bb31b88 RCX: 0000000000000040
RDX: 0000000000000000 RSI: ffffffff8e3a7c7f RDI: 0000000000000001
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000cc5
R13: ffffc90003816ad8 R14: 0000000000000000 R15: 0000000000000000
spin_unlock_irq include/linux/spinlock.h:402 [inline]
shmem_add_to_page_cache+0x874/0xcd0 mm/shmem.c:938
shmem_alloc_and_add_folio+0x558/0xd40 mm/shmem.c:1985
shmem_get_folio_gfp+0x6ad/0x1910 mm/shmem.c:2512
shmem_get_folio mm/shmem.c:2618 [inline]
shmem_write_begin+0x1a4/0x420 mm/shmem.c:3249
generic_perform_write+0x292/0xa40 mm/filemap.c:4364
shmem_file_write_iter+0x10e/0x140 mm/shmem.c:3424
__kernel_write_iter+0x2ac/0x930 fs/read_write.c:621
dump_emit_page fs/coredump.c:1293 [inline]
dump_user_range+0x3f9/0xad0 fs/coredump.c:1367
elf_core_dump+0x2d68/0x3d20 fs/binfmt_elf.c:2109
coredump_write fs/coredump.c:1047 [inline]
do_coredump fs/coredump.c:1126 [inline]
vfs_coredump+0x281a/0x54a0 fs/coredump.c:1195
get_signal+0x1f2a/0x21e0 kernel/signal.c:3031
arch_do_signal_or_restart+0x91/0x7e0 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
exit_to_user_mode_loop+0x139/0x700 kernel/entry/common.c:101
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
do_syscall_64+0x666/0x870 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fcd8619e0d9
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:00007fcd8705f0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: 00000000000000ca RBX: 00007fcd86425fa8 RCX: 00007fcd8619e0d9
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007fcd86425fac
RBP: 00007fcd86425fa0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fcd86426038 R14: 00007ffcec4674f0 R15: 00007ffcec4675d8
Allocated by task 14162:
kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
kasan_save_track+0x14/0x30 mm/kasan/common.c:78
poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
__kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415
kasan_kmalloc include/linux/kasan.h:263 [inline]
__kmalloc_cache_noprof+0x2e5/0x6c0 mm/slub.c:5489
_kmalloc_noprof include/linux/slab.h:988 [inline]
_kzalloc_noprof include/linux/slab.h:1309 [inline]
llc_sap_alloc net/llc/llc_core.c:29 [inline]
llc_sap_open+0x120/0x3b0 net/llc/llc_core.c:96
llc_ui_autobind.isra.0+0x2ae/0x580 net/llc/af_llc.c:301
llc_ui_connect+0x582/0xdb0 net/llc/af_llc.c:498
__sys_connect_file+0x141/0x1a0 net/socket.c:2160
__sys_connect+0x141/0x170 net/socket.c:2179
__do_sys_connect net/socket.c:2185 [inline]
__se_sys_connect net/socket.c:2182 [inline]
__x64_sys_connect+0x72/0xb0 net/socket.c:2182
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 14074:
kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
kasan_save_track+0x14/0x30 mm/kasan/common.c:78
kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:253 [inline]
__kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285
kasan_slab_free include/linux/kasan.h:235 [inline]
slab_free_hook mm/slub.c:2677 [inline]
__rcu_free_sheaf_prepare+0x5d/0x2f0 mm/slub.c:2928
rcu_free_sheaf+0x1a/0xe0 mm/slub.c:5978
rcu_do_batch kernel/rcu/tree.c:2645 [inline]
rcu_core+0x5a2/0x10d0 kernel/rcu/tree.c:2897
handle_softirqs+0x1ea/0x9b0 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0x162/0x210 kernel/softirq.c:735
irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
sysvec_apic_timer_interrupt+0xa3/0xc0 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 ffff88802b618000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 16 bytes inside of
freed 2048-byte region [ffff88802b618000, ffff88802b618800)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2b618
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 ffff88801c028000 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800080008 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801c028000 dead000000000100 dead000000000122
head: 0000000000000000 0000000800080008 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 13, tgid 13 (kworker/u8:1), ts 7357308291, free_ts 0
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1859
prep_new_page mm/page_alloc.c:1867 [inline]
get_page_from_freelist+0xf48/0x3530 mm/page_alloc.c:3946
__alloc_frozen_pages_noprof+0x299/0x2dc0 mm/page_alloc.c:5304
alloc_slab_page mm/slub.c:3266 [inline]
allocate_slab mm/slub.c:3380 [inline]
new_slab+0xa2/0x640 mm/slub.c:3426
refill_objects+0xe3/0x410 mm/slub.c:7310
refill_sheaf mm/slub.c:2804 [inline]
__pcs_replace_empty_main+0x376/0x680 mm/slub.c:4675
alloc_from_pcs mm/slub.c:4773 [inline]
slab_alloc_node mm/slub.c:4905 [inline]
__do_kmalloc_node mm/slub.c:5333 [inline]
__kmalloc_noprof+0x66d/0x820 mm/slub.c:5359
_kmalloc_noprof include/linux/slab.h:992 [inline]
_kzalloc_noprof include/linux/slab.h:1309 [inline]
scsi_alloc_target+0x12f/0xc70 drivers/scsi/scsi_scan.c:505
__scsi_scan_target+0x124/0x570 drivers/scsi/scsi_scan.c:1780
scsi_scan_channel drivers/scsi/scsi_scan.c:1885 [inline]
scsi_scan_channel+0x13d/0x1e0 drivers/scsi/scsi_scan.c:1861
scsi_scan_host_selected+0x2fe/0x3e0 drivers/scsi/scsi_scan.c:1914
do_scsi_scan_host+0x1f4/0x270 drivers/scsi/scsi_scan.c:2047
do_scan_async+0x42/0x480 drivers/scsi/scsi_scan.c:2057
async_run_entry_fn+0x9f/0x580 kernel/async.c:129
process_one_work+0xa23/0x1940 kernel/workqueue.c:3322
process_scheduled_works kernel/workqueue.c:3405 [inline]
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486
page_owner free stack trace missing
Memory state around the buggy address:
ffff88802b617f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88802b617f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88802b618000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88802b618080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802b618100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
0: 90 nop
1: f3 0f 1e fa endbr64
5: 53 push %rbx
6: 48 8b 74 24 08 mov 0x8(%rsp),%rsi
b: 48 89 fb mov %rdi,%rbx
e: 48 83 c7 18 add $0x18,%rdi
12: e8 3a e2 24 f6 call 0xf624e251
17: 48 89 df mov %rbx,%rdi
1a: e8 c2 31 25 f6 call 0xf62531e1
1f: e8 5d 9b 51 f6 call 0xf6519b81
24: fb sti
25: bf 01 00 00 00 mov $0x1,%edi
* 2a: e8 72 3f 14 f6 call 0xf6143fa1 <-- trapping instruction
2f: 65 8b 05 db 76 c3 08 mov %gs:0x8c376db(%rip),%eax # 0x8c37711
36: 85 c0 test %eax,%eax
38: 74 06 je 0x40
3a: 5b pop %rbx
3b: e9 81 4b 00 00 jmp 0x4bc1