==================================================================
BUG: KASAN: use-after-free in ax25_heartbeat_expiry+0x10c/0x130 net/ax25/ax25_timer.c:125
Read of size 4 at addr ffff88801ecf5f50 by task udevd/4178
CPU: 1 PID: 4178 Comm: udevd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
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
ax25_heartbeat_expiry+0x10c/0x130 net/ax25/ax25_timer.c:125
call_timer_fn+0x17b/0x540 kernel/time/timer.c:1648
expire_timers kernel/time/timer.c:1699 [inline]
__run_timers+0x53e/0x800 kernel/time/timer.c:1970
run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1983
handle_softirqs+0x339/0x830 kernel/softirq.c:576
__do_softirq kernel/softirq.c:610 [inline]
invoke_softirq kernel/softirq.c:450 [inline]
__irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659
irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:__seqprop_spinlock_sequence include/linux/seqlock.h:277 [inline]
RIP: 0010:read_mems_allowed_begin include/linux/cpuset.h:153 [inline]
RIP: 0010:get_any_partial mm/slub.c:2198 [inline]
RIP: 0010:get_partial mm/slub.c:2241 [inline]
RIP: 0010:___slab_alloc+0x7c6/0xdd0 mm/slub.c:3008
Code: 24 38 f7 44 24 38 00 02 00 00 75 0c 41 f7 c7 00 02 00 00 74 15 fb eb 12 e8 37 ef fe 07 41 f7 c7 00 02 00 00 74 04 eb ed f3 90 <44> 8b a5 20 13 00 00 41 f6 c4 01 75 f1 44 8b 7c 24 08 e9 26 fe ff
RSP: 0018:ffffc90002eef830 EFLAGS: 00000206
RAX: dee37c22bb3c3e00 RBX: ffff888016c42140 RCX: dee37c22bb3c3e00
RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: ffffffff8a79f980
RBP: ffff88807a788000 R08: ffffffff901d4177 R09: 1ffffffff203a82e
R10: dffffc0000000000 R11: fffffbfff203a82f R12: ffff88807a789328
R13: ffffffff81bd8dcd R14: ffffffff7fff0000 R15: 0000000000000246
__slab_alloc mm/slub.c:3100 [inline]
slab_alloc_node mm/slub.c:3191 [inline]
slab_alloc mm/slub.c:3233 [inline]
__kmalloc+0x1cd/0x330 mm/slub.c:4408
kmalloc include/linux/slab.h:612 [inline]
tomoyo_realpath_from_path+0x118/0x610 security/tomoyo/realpath.c:254
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_path2_perm+0x27e/0x840 security/tomoyo/file.c:922
tomoyo_path_rename+0xfd/0x150 security/tomoyo/tomoyo.c:278
security_path_rename+0x1dc/0x280 security/security.c:1205
do_renameat2+0x69b/0xf60 fs/namei.c:4980
__do_sys_rename fs/namei.c:5039 [inline]
__se_sys_rename fs/namei.c:5037 [inline]
__x64_sys_rename+0x82/0x90 fs/namei.c:5037
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
RIP: 0033:0x7f7a809a7cc7
Code: e8 5e a7 09 00 f7 d8 19 c0 5b c3 0f 1f 84 00 00 00 00 00 b8 ff ff ff ff 5b c3 66 0f 1f 84 00 00 00 00 00 b8 52 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 8b 15 01 61 17 00 f7 d8 64 89 02 b8
RSP: 002b:00007ffd4e1dae78 EFLAGS: 00000206 ORIG_RAX: 0000000000000052
RAX: ffffffffffffffda RBX: 00005589d0e849d0 RCX: 00007f7a809a7cc7
RDX: 00005589d0e61010 RSI: 00007ffd4e1dae90 RDI: 00007ffd4e1db290
RBP: 00005589d0e79e00 R08: 00000000000001e0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 00007ffd4e1dae90
R13: 00007ffd4e1db290 R14: 0000000000000000 R15: 00005589d0e62620
Allocated by task 4321:
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+0xb5/0xf0 mm/kasan/common.c:522
kmalloc include/linux/slab.h:607 [inline]
kzalloc include/linux/slab.h:738 [inline]
ax25_dev_device_up+0x50/0x580 net/ax25/ax25_dev.c:55
ax25_device_event+0x483/0x4f0 net/ax25/af_ax25.c:139
notifier_call_chain kernel/notifier.c:83 [inline]
raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:391
call_netdevice_notifiers_extack net/core/dev.c:2074 [inline]
call_netdevice_notifiers net/core/dev.c:2088 [inline]
__dev_notify_flags+0x194/0x300 net/core/dev.c:8917
dev_change_flags+0xe3/0x1a0 net/core/dev.c:8955
dev_ifsioc+0x130/0xd50 net/core/dev_ioctl.c:324
dev_ioctl+0x545/0xe30 net/core/dev_ioctl.c:572
sock_do_ioctl+0x245/0x320 net/socket.c:1161
sock_ioctl+0x4d2/0x710 net/socket.c:1266
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
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 4393:
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+0xea/0x170 mm/slub.c:1736
slab_free mm/slub.c:3504 [inline]
kfree+0xef/0x2a0 mm/slub.c:4564
ax25_dev_put include/net/ax25.h:302 [inline]
ax25_release+0x661/0x870 net/ax25/af_ax25.c:1062
__sock_release net/socket.c:651 [inline]
sock_close+0xd5/0x240 net/socket.c:1345
__fput+0x234/0x930 fs/file_table.c:311
task_work_run+0x125/0x1a0 kernel/task_work.c:188
exit_task_work include/linux/task_work.h:33 [inline]
do_exit+0x626/0x20c0 kernel/exit.c:883
do_group_exit+0x12e/0x300 kernel/exit.c:997
get_signal+0x6ca/0x12c0 kernel/signal.c:2900
arch_do_signal_or_restart+0xe7/0x12c0 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
ret_from_fork+0x15/0x30 arch/x86/entry/entry_64.S:280
The buggy address belongs to the object at ffff88801ecf5f00
which belongs to the cache kmalloc-192 of size 192
The buggy address is located 80 bytes inside of
192-byte region [ffff88801ecf5f00, ffff88801ecf5fc0)
The buggy address belongs to the page:
page:ffffea00007b3d40 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1ecf5
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 0000000000000000 dead000000000122 ffff888016c41a00
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 4313, ts 63370024176, free_ts 63366606582
prep_new_page mm/page_alloc.c:2426 [inline]
get_page_from_freelist+0x1bbd/0x1ca0 mm/page_alloc.c:4192
__alloc_pages+0x1ee/0x480 mm/page_alloc.c:5501
__alloc_pages_node include/linux/gfp.h:570 [inline]
alloc_slab_page mm/slub.c:1782 [inline]
allocate_slab mm/slub.c:1917 [inline]
new_slab+0xb6/0x4b0 mm/slub.c:1980
___slab_alloc+0x80a/0xdd0 mm/slub.c:3013
__slab_alloc mm/slub.c:3100 [inline]
slab_alloc_node mm/slub.c:3191 [inline]
__kmalloc_node+0x200/0x3b0 mm/slub.c:4456
kmalloc_array_node include/linux/slab.h:700 [inline]
kcalloc_node include/linux/slab.h:705 [inline]
memcg_alloc_page_obj_cgroups+0x81/0x120 mm/memcontrol.c:2839
memcg_slab_post_alloc_hook mm/slab.h:313 [inline]
slab_post_alloc_hook+0xba/0x380 mm/slab.h:526
slab_alloc_node mm/slub.c:3225 [inline]
slab_alloc mm/slub.c:3233 [inline]
kmem_cache_alloc+0x100/0x290 mm/slub.c:3238
__d_alloc+0x2a/0x6f0 fs/dcache.c:1749
d_alloc+0x4a/0x250 fs/dcache.c:1828
lookup_one_qstr_excl+0xc6/0x240 fs/namei.c:1567
filename_create+0x23a/0x470 fs/namei.c:3844
do_symlinkat+0xbc/0x6b0 fs/namei.c:4456
__do_sys_symlinkat fs/namei.c:4483 [inline]
__se_sys_symlinkat fs/namei.c:4480 [inline]
__x64_sys_symlinkat+0x95/0xa0 fs/namei.c:4480
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
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1340 [inline]
free_pcp_prepare mm/page_alloc.c:1391 [inline]
free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317
free_unref_page+0x8f/0x2a0 mm/page_alloc.c:3396
free_slab mm/slub.c:2020 [inline]
discard_slab mm/slub.c:2026 [inline]
__unfreeze_partials+0x1a5/0x200 mm/slub.c:2512
put_cpu_partial+0x12d/0x190 mm/slub.c:2592
qlist_free_all+0x35/0x90 mm/kasan/quarantine.c:176
kasan_quarantine_reduce+0x150/0x160 mm/kasan/quarantine.c:283
__kasan_slab_alloc+0x2f/0xd0 mm/kasan/common.c:444
kasan_slab_alloc include/linux/kasan.h:254 [inline]
slab_post_alloc_hook+0x4c/0x380 mm/slab.h:519
slab_alloc_node mm/slub.c:3225 [inline]
slab_alloc mm/slub.c:3233 [inline]
__kmalloc+0x127/0x330 mm/slub.c:4408
kmalloc include/linux/slab.h:612 [inline]
kzalloc include/linux/slab.h:738 [inline]
tomoyo_encode2 security/tomoyo/realpath.c:45 [inline]
tomoyo_encode+0x27e/0x540 security/tomoyo/realpath.c:80
tomoyo_path_perm+0x349/0x5d0 security/tomoyo/file.c:831
tomoyo_path_symlink+0xa8/0xf0 security/tomoyo/tomoyo.c:199
security_path_symlink+0xdc/0x130 security/security.c:1179
do_symlinkat+0x105/0x6b0 fs/namei.c:4461
__do_sys_symlinkat fs/namei.c:4483 [inline]
__se_sys_symlinkat fs/namei.c:4480 [inline]
__x64_sys_symlinkat+0x95/0xa0 fs/namei.c:4480
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
Memory state around the buggy address:
ffff88801ecf5e00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88801ecf5e80: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
>ffff88801ecf5f00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88801ecf5f80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff88801ecf6000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
----------------
Code disassembly (best guess):
0: 24 38 and $0x38,%al
2: f7 44 24 38 00 02 00 testl $0x200,0x38(%rsp)
9: 00
a: 75 0c jne 0x18
c: 41 f7 c7 00 02 00 00 test $0x200,%r15d
13: 74 15 je 0x2a
15: fb sti
16: eb 12 jmp 0x2a
18: e8 37 ef fe 07 call 0x7feef54
1d: 41 f7 c7 00 02 00 00 test $0x200,%r15d
24: 74 04 je 0x2a
26: eb ed jmp 0x15
28: f3 90 pause
* 2a: 44 8b a5 20 13 00 00 mov 0x1320(%rbp),%r12d <-- trapping instruction
31: 41 f6 c4 01 test $0x1,%r12b
35: 75 f1 jne 0x28
37: 44 8b 7c 24 08 mov 0x8(%rsp),%r15d
3c: e9 .byte 0xe9
3d: 26 fe es (bad)
3f: ff .byte 0xff