==================================================================
BUG: KASAN: slab-use-after-free in ax25_disconnect+0x44e/0x4d0 net/ax25/ax25_subr.c:283
Read of size 8 at addr ffff888079a6abc0 by task syz.4.5990/25418
CPU: 0 UID: 0 PID: 25418 Comm: syz.4.5990 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
<IRQ>
__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/0x1d0 mm/kasan/report.c:595
ax25_disconnect+0x44e/0x4d0 net/ax25/ax25_subr.c:283
ax25_std_t1timer_expiry+0x4af/0x550 net/ax25/ax25_std_timer.c:126
ax25_t1timer_expiry+0xc9/0x100 net/ax25/ax25_timer.c:159
call_timer_fn+0x19a/0x640 kernel/time/timer.c:1748
expire_timers kernel/time/timer.c:1799 [inline]
__run_timers+0x75f/0xaf0 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/0xa00 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:1061 [inline]
sysvec_apic_timer_interrupt+0xa3/0xc0 arch/x86/kernel/apic/apic.c:1061
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lockdep_unregister_key+0x12b/0x1d0 kernel/locking/lockdep.c:6616
Code: e8 da dd ff ff 48 83 2d 5a b8 4e 14 01 89 c3 e8 2b e0 ff ff 9c 58 f6 c4 02 0f 85 8a 00 00 00 f7 c5 00 02 00 00 74 01 fb 84 db <75> 40 5b 5d 41 5c e9 0a 9d 09 00 9c 58 f6 c4 02 0f 84 16 ff ff ff
RSP: 0018:ffffc9000d60fa60 EFLAGS: 00000246
RAX: 0000000000000046 RBX: 0000000000000000 RCX: 0000000000000001
RDX: 0000000000000000 RSI: ffffffff8e04c445 RDI: ffffffff8c1c1f00
RBP: 0000000000000246 R08: 0000000000009707 R09: ffffffff9634f9ee
R10: 0000000000000200 R11: 0000000000000000 R12: ffffffff979acc48
R13: ffff888028094000 R14: ffff8880280944d0 R15: 0000000000000100
qdisc_lock_uninit include/net/pkt_sched.h:332 [inline]
__qdisc_destroy+0x172/0x540 net/sched/sch_generic.c:1102
qdisc_put+0xb0/0xf0 net/sched/sch_generic.c:1128
shutdown_scheduler_queue+0xa5/0x160 net/sched/sch_generic.c:1181
netdev_for_each_tx_queue include/linux/netdevice.h:2689 [inline]
dev_shutdown+0xb3/0x440 net/sched/sch_generic.c:1490
unregister_netdevice_many_notify+0xd56/0x24f0 net/core/dev.c:12452
unregister_netdevice_many net/core/dev.c:12527 [inline]
unregister_netdevice_queue net/core/dev.c:12337 [inline]
unregister_netdevice_queue+0x30b/0x3c0 net/core/dev.c:12327
unregister_netdevice include/linux/netdevice.h:3427 [inline]
__tun_detach+0x1173/0x1480 drivers/net/tun.c:621
tun_detach drivers/net/tun.c:637 [inline]
tun_chr_close+0xc2/0x220 drivers/net/tun.c:3438
__fput+0x3ff/0xb50 fs/file_table.c:510
task_work_run+0x150/0x240 kernel/task_work.c:233
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
__exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
exit_to_user_mode_loop+0x100/0x4a0 kernel/entry/common.c:98
__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:238 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
do_syscall_64+0x706/0xf80 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff13b59c819
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:00007ffe3151cdb8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007ff13b817da0 RCX: 00007ff13b59c819
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007ff13b817da0 R08: 00007ff13b8163f8 R09: 0000000000000000
R10: 00000000003ff6b0 R11: 0000000000000246 R12: 000000000013b8cc
R13: 00007ff13b81645c R14: 000000000013b794 R15: 00007ff13b816450
</TASK>
Allocated by task 15354:
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
kmalloc_noprof include/linux/slab.h:950 [inline]
kzalloc_noprof include/linux/slab.h:1188 [inline]
ax25_create_cb+0x40/0x660 net/ax25/af_ax25.c:531
ax25_send_frame+0x233/0xb70 net/ax25/ax25_out.c:67
rose_send_frame+0xfa/0x2a0 net/rose/rose_link.c:106
rose_transmit_restart_request+0x1b8/0x250 net/rose/rose_link.c:198
rose_transmit_link+0x32f/0x5d0 net/rose/rose_link.c:284
rose_write_internal+0x3ee/0x1700 net/rose/rose_subr.c:198
rose_connect+0x715/0x1a00 net/rose/af_rose.c:886
__sys_connect_file+0x141/0x1a0 net/socket.c:2148
__sys_connect+0x141/0x170 net/socket.c:2167
__do_sys_connect net/socket.c:2173 [inline]
__se_sys_connect net/socket.c:2170 [inline]
__x64_sys_connect+0x72/0xb0 net/socket.c:2170
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 0:
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:2689 [inline]
slab_free mm/slub.c:6246 [inline]
kfree+0x223/0x6c0 mm/slub.c:6561
ax25_cb_put include/net/ax25.h:277 [inline]
ax25_cb_put include/net/ax25.h:273 [inline]
ax25_destroy_socket+0x42f/0x650 net/ax25/af_ax25.c:355
ax25_std_heartbeat_expiry+0x303/0x4b0 net/ax25/ax25_std_timer.c:51
ax25_heartbeat_expiry+0xce/0x130 net/ax25/ax25_timer.c:140
call_timer_fn+0x19a/0x640 kernel/time/timer.c:1748
expire_timers kernel/time/timer.c:1799 [inline]
__run_timers+0x75f/0xaf0 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/0xa00 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:1061 [inline]
sysvec_apic_timer_interrupt+0xa3/0xc0 arch/x86/kernel/apic/apic.c:1061
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
The buggy address belongs to the object at ffff888079a6a800
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 960 bytes inside of
freed 1024-byte region [ffff888079a6a800, ffff888079a6ac00)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888079a68000 pfn:0x79a68
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 ffff88813fe87dc0 ffffea000095be10 ffffea000150a010
raw: ffff888079a68000 0000000800100008 00000000f5000000 0000000000000000
head: 00fff00000000240 ffff88813fe87dc0 ffffea000095be10 ffffea000150a010
head: ffff888079a68000 0000000800100008 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 6141, tgid 6141 (syz-executor), ts 100256382752, free_ts 100256192495
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x153/0x170 mm/page_alloc.c:1858
prep_new_page mm/page_alloc.c:1866 [inline]
get_page_from_freelist+0x11a6/0x33b0 mm/page_alloc.c:3946
__alloc_frozen_pages_noprof+0x27c/0x2bc0 mm/page_alloc.c:5226
alloc_slab_page mm/slub.c:3278 [inline]
allocate_slab mm/slub.c:3467 [inline]
new_slab+0xa6/0x6c0 mm/slub.c:3525
refill_objects+0x277/0x420 mm/slub.c:7251
refill_sheaf mm/slub.c:2816 [inline]
__pcs_replace_empty_main+0x375/0x650 mm/slub.c:4651
alloc_from_pcs mm/slub.c:4749 [inline]
slab_alloc_node mm/slub.c:4883 [inline]
__do_kmalloc_node mm/slub.c:5294 [inline]
__kvmalloc_node_noprof+0x7da/0xa00 mm/slub.c:6828
bucket_table_alloc.isra.0+0x88/0x460 lib/rhashtable.c:186
rhashtable_init_noprof+0x43b/0x7d0 lib/rhashtable.c:1076
simple_xattrs_init fs/xattr.c:1618 [inline]
simple_xattrs_alloc+0x5c/0xd0 fs/xattr.c:1641
class_simple_xattrs_constructor include/linux/xattr.h:165 [inline]
shmem_initxattrs+0x7d/0x6c0 mm/shmem.c:4237
security_inode_init_security+0x242/0x370 security/security.c:1370
shmem_symlink+0x163/0xa00 mm/shmem.c:4098
vfs_symlink fs/namei.c:5643 [inline]
vfs_symlink+0x178/0x4d0 fs/namei.c:5622
filename_symlinkat+0x2a6/0x560 fs/namei.c:5668
__do_sys_symlinkat fs/namei.c:5688 [inline]
__se_sys_symlinkat fs/namei.c:5683 [inline]
__x64_sys_symlinkat+0x9c/0xe0 fs/namei.c:5683
page last free pid 6141 tgid 6141 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1402 [inline]
__free_frozen_pages+0x747/0x1040 mm/page_alloc.c:2943
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x47/0xf0 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:350
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4569 [inline]
slab_alloc_node mm/slub.c:4898 [inline]
__do_kmalloc_node mm/slub.c:5294 [inline]
__kmalloc_noprof+0x2b9/0x850 mm/slub.c:5307
kmalloc_noprof include/linux/slab.h:954 [inline]
kzalloc_noprof include/linux/slab.h:1188 [inline]
tomoyo_encode2+0xfb/0x3c0 security/tomoyo/realpath.c:45
tomoyo_encode+0x29/0x50 security/tomoyo/realpath.c:80
tomoyo_path_perm+0x3a7/0x460 security/tomoyo/file.c:836
tomoyo_path_symlink+0x97/0xe0 security/tomoyo/tomoyo.c:212
security_path_symlink+0x152/0x2d0 security/security.c:1502
filename_symlinkat+0x122/0x560 fs/namei.c:5666
__do_sys_symlinkat fs/namei.c:5688 [inline]
__se_sys_symlinkat fs/namei.c:5683 [inline]
__x64_sys_symlinkat+0x9c/0xe0 fs/namei.c:5683
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Memory state around the buggy address:
ffff888079a6aa80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888079a6ab00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888079a6ab80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888079a6ac00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888079a6ac80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
----------------
Code disassembly (best guess):
0: e8 da dd ff ff call 0xffffdddf
5: 48 83 2d 5a b8 4e 14 subq $0x1,0x144eb85a(%rip) # 0x144eb867
c: 01
d: 89 c3 mov %eax,%ebx
f: e8 2b e0 ff ff call 0xffffe03f
14: 9c pushf
15: 58 pop %rax
16: f6 c4 02 test $0x2,%ah
19: 0f 85 8a 00 00 00 jne 0xa9
1f: f7 c5 00 02 00 00 test $0x200,%ebp
25: 74 01 je 0x28
27: fb sti
28: 84 db test %bl,%bl
* 2a: 75 40 jne 0x6c <-- trapping instruction
2c: 5b pop %rbx
2d: 5d pop %rbp
2e: 41 5c pop %r12
30: e9 0a 9d 09 00 jmp 0x99d3f
35: 9c pushf
36: 58 pop %rax
37: f6 c4 02 test $0x2,%ah
3a: 0f 84 16 ff ff ff je 0xffffff56