==================================================================
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 ffff888029e85010 by task syz.4.1063/12713
CPU: 1 UID: 0 PID: 12713 Comm: syz.4.1063 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+0x198/0x5f0 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+0x1e6/0x9d0 kernel/softirq.c:645
__do_softirq kernel/softirq.c:679 [inline]
invoke_softirq kernel/softirq.c:519 [inline]
__irq_exit_rcu+0x194/0x210 kernel/softirq.c:767
irq_exit_rcu+0x9/0x30 kernel/softirq.c:784
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:schedule_debug kernel/sched/core.c:6088 [inline]
RIP: 0010:__schedule+0x18f/0x6920 kernel/sched/core.c:7119
Code: ff ff ff 4c 8b 60 20 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 80 3c 02 00 0f 85 09 54 00 00 49 81 3c 24 9d 6e ac 57 <0f> 85 68 67 00 00 48 8b 85 70 ff ff ff 48 8d 48 18 48 89 8d f8 fe
RSP: 0018:ffffc900042b7840 EFLAGS: 00000246
RAX: dffffc0000000000 RBX: 0000000000000001 RCX: ffffffff8bcf578f
RDX: 1ffff92000856000 RSI: ffffffff8c622200 RDI: ffff88802b889f60
RBP: ffffc900042b7990 R08: 0000000000000000 R09: fffffbfff228a56b
R10: ffffffff91452b5f R11: 0000000000000001 R12: ffffc900042b0000
R13: ffff888029e85001 R14: ffff8880b853c040 R15: ffffffff948df548
preempt_schedule_common+0x3c/0xb0 kernel/sched/core.c:7449
preempt_schedule_thunk+0x16/0x40 arch/x86/entry/thunk.S:12
__kfree_rcu_sheaf+0x33d/0x870 mm/slub.c:6207
kfree_rcu_sheaf mm/slab_common.c:1688 [inline]
kvfree_call_rcu+0x1c0/0x4f0 mm/slab_common.c:2037
llc_sap_close+0x158/0x1c0 net/llc/llc_core.c:124
llc_sap_put include/net/llc.h:126 [inline]
llc_ui_release+0x449/0x5d0 net/llc/af_llc.c:218
__sock_release+0xb3/0x260 net/socket.c:735
sock_close+0x1c/0x30 net/socket.c:1526
__fput+0x3ff/0xb50 fs/file_table.c:512
task_work_run+0x150/0x240 kernel/task_work.c:233
get_signal+0x1bd/0x21e0 kernel/signal.c:2811
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:336 [inline]
do_syscall_64+0x661/0x790 arch/x86/entry/syscall_64.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f440059e159
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:00007f44014a9028 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: fffffffffffffe00 RBX: 00007f4400826090 RCX: 00007f440059e159
RDX: 0000000000000010 RSI: 0000200000000180 RDI: 000000000000000a
RBP: 00007f4400635024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4400826128 R14: 00007f4400826090 R15: 00007ffd3084cad8
Allocated by task 12713:
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+0x2f8/0x6d0 mm/slub.c:5563
_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+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
connect_socket net/socket.c:2141 [inline]
connect_socket net/socket.c:2131 [inline]
__sys_connect_file+0x146/0x1a0 net/socket.c:2166
__sys_connect+0x141/0x170 net/socket.c:2183
__do_sys_connect net/socket.c:2189 [inline]
__se_sys_connect net/socket.c:2186 [inline]
__x64_sys_connect+0x72/0xb0 net/socket.c:2186
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 12334:
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:2748 [inline]
__rcu_free_sheaf_prepare+0x5d/0x300 mm/slub.c:3009
rcu_free_sheaf+0x1a/0xe0 mm/slub.c:6052
rcu_do_batch kernel/rcu/tree.c:2650 [inline]
rcu_core+0x5f0/0x1260 kernel/rcu/tree.c:2919
handle_softirqs+0x1e6/0x9d0 kernel/softirq.c:645
__do_softirq kernel/softirq.c:679 [inline]
invoke_softirq kernel/softirq.c:519 [inline]
__irq_exit_rcu+0x194/0x210 kernel/softirq.c:767
irq_exit_rcu+0x9/0x30 kernel/softirq.c:784
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 ffff888029e85000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 16 bytes inside of
freed 2048-byte region [ffff888029e85000, ffff888029e85800)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888029e86000 pfn:0x29e80
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000240(workingset|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000240 ffff88801c02e000 ffffea0000ad1210 ffffea0001473610
raw: ffff888029e86000 0000000000080007 00000000f5000000 0000000000000000
head: 00fff00000000240 ffff88801c02e000 ffffea0000ad1210 ffffea0001473610
head: ffff888029e86000 0000000000080007 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 0xd2000(__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 6547465359
set_page_owner include/linux/page_owner.h:33 [inline]
post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1871
prep_new_page mm/page_alloc.c:1879 [inline]
get_page_from_freelist+0x110d/0x35d0 mm/page_alloc.c:3943
__alloc_frozen_pages_noprof+0x2eb/0x3300 mm/page_alloc.c:5436
alloc_slab_page mm/slub.c:3347 [inline]
allocate_slab mm/slub.c:3462 [inline]
new_slab+0xa9/0x6e0 mm/slub.c:3513
refill_objects+0xe3/0x410 mm/slub.c:7410
refill_sheaf mm/slub.c:2885 [inline]
__pcs_replace_empty_main+0x35e/0x650 mm/slub.c:4774
alloc_from_pcs mm/slub.c:4850 [inline]
slab_alloc_node mm/slub.c:4984 [inline]
__kmalloc_cache_noprof+0x4f4/0x6d0 mm/slub.c:5559
_kmalloc_noprof include/linux/slab.h:991 [inline]
_kzalloc_noprof include/linux/slab.h:1312 [inline]
device_create_groups_vargs+0x8a/0x270 drivers/base/core.c:4440
device_create+0xed/0x130 drivers/base/core.c:4497
bdi_register_va+0x114/0x820 mm/backing-dev.c:1099
bdi_register+0xc7/0x100 mm/backing-dev.c:1131
__add_disk+0xa6d/0xe40 block/genhd.c:529
add_disk_fwnode+0x118/0x480 block/genhd.c:593
add_mtd_blktrans_dev+0xd0b/0x1520 drivers/mtd/mtd_blkdevs.c:382
mtdblock_add_mtd+0x1cc/0x270 drivers/mtd/mtdblock.c:333
blktrans_notify_add drivers/mtd/mtd_blkdevs.c:464 [inline]
blktrans_notify_add+0xa2/0xf0 drivers/mtd/mtd_blkdevs.c:456
page last free pid 188 tgid 188 ts 6523447792 stack trace:
reset_page_owner include/linux/page_owner.h:26 [inline]
__free_pages_prepare mm/page_alloc.c:1418 [inline]
free_pages_prepare+0x586/0xe00 mm/page_alloc.c:1463
__free_contig_range_common+0x14f/0x250 mm/page_alloc.c:7072
__free_contig_range mm/page_alloc.c:7117 [inline]
free_pages_bulk+0x12a/0x200 mm/page_alloc.c:5322
vm_area_free_pages+0xb2/0x2a0 mm/vmalloc.c:3461
vfree mm/vmalloc.c:3510 [inline]
vfree+0xf7/0x6d0 mm/vmalloc.c:3484
delayed_vfree_work+0x56/0x80 mm/vmalloc.c:3414
process_one_work+0xac7/0x1b10 kernel/workqueue.c:3387
process_scheduled_works kernel/workqueue.c:3470 [inline]
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3551
kthread+0x373/0x450 kernel/kthread.c:436
ret_from_fork+0x730/0xd60 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:
ffff888029e84f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888029e84f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888029e85000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888029e85080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888029e85100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess), 2 bytes skipped:
0: ff 4c 8b 60 decl 0x60(%rbx,%rcx,4)
4: 20 48 b8 and %cl,-0x48(%rax)
7: 00 00 add %al,(%rax)
9: 00 00 add %al,(%rax)
b: 00 fc add %bh,%ah
d: ff lcall (bad)
e: df 4c 89 e2 fisttps -0x1e(%rcx,%rcx,4)
12: 48 c1 ea 03 shr $0x3,%rdx
16: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1)
1a: 0f 85 09 54 00 00 jne 0x5429
20: 49 81 3c 24 9d 6e ac cmpq $0x57ac6e9d,(%r12)
27: 57
* 28: 0f 85 68 67 00 00 jne 0x6796 <-- trapping instruction
2e: 48 8b 85 70 ff ff ff mov -0x90(%rbp),%rax
35: 48 8d 48 18 lea 0x18(%rax),%rcx
39: 48 rex.W
3a: 89 .byte 0x89
3b: 8d lea (bad),%edi
3c: f8 clc
3d: fe .byte 0xfe