==================================================================
BUG: KASAN: slab-use-after-free in ax25_heartbeat_expiry+0x115/0x140 net/ax25/ax25_timer.c:127
Read of size 4 at addr ffff888035f08060 by task syz.4.2176/14423
CPU: 1 UID: 0 PID: 14423 Comm: syz.4.2176 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0xba/0x230 mm/kasan/report.c:482
kasan_report+0x117/0x150 mm/kasan/report.c:595
ax25_heartbeat_expiry+0x115/0x140 net/ax25/ax25_timer.c:127
call_timer_fn+0x192/0x640 kernel/time/timer.c:1748
expire_timers kernel/time/timer.c:1799 [inline]
__run_timers kernel/time/timer.c:2373 [inline]
__run_timer_base+0x652/0x8b0 kernel/time/timer.c:2385
run_timer_base kernel/time/timer.c:2394 [inline]
run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2404
handle_softirqs+0x22a/0x870 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0x5f/0x150 kernel/softirq.c:723
irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1056
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x47/0x80 kernel/locking/spinlock.c:194
Code: f7 e8 fd cc ec f5 f7 c3 00 02 00 00 74 05 e8 90 38 18 f6 9c 58 a9 00 02 00 00 75 27 f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 e4 87 de f5 65 8b 05 0d c0 67 07 85 c0 74 18 5b 41 5e c3 cc cc
RSP: 0018:ffffc9000c1f67e8 EFLAGS: 00000206
RAX: 0000000000000006 RBX: 0000000000000292 RCX: 0000000080000001
RDX: 0000000000000006 RSI: ffffffff8df2c159 RDI: 0000000000000001
RBP: 0000000000000000 R08: ffffffff9011b3b7 R09: 1ffffffff2023676
R10: dffffc0000000000 R11: fffffbfff2023677 R12: ffff888089000000
R13: ffff888088c00000 R14: ffffffff9a509c70 R15: 000000000000034e
__debug_check_no_obj_freed lib/debugobjects.c:1125 [inline]
debug_check_no_obj_freed+0x52e/0x550 lib/debugobjects.c:1146
__free_pages_prepare mm/page_alloc.c:1440 [inline]
__free_pages_ok+0x5a1/0xc50 mm/page_alloc.c:1614
ptr_ring_resize_multiple_bh_noprof include/linux/ptr_ring.h:655 [inline]
skb_array_resize_multiple_bh_noprof include/linux/skb_array.h:208 [inline]
pfifo_fast_change_tx_queue_len+0x965/0xa40 net/sched/sch_generic.c:938
qdisc_change_tx_queue_len net/sched/sch_generic.c:1409 [inline]
dev_qdisc_change_tx_queue_len+0x3a8/0x510 net/sched/sch_generic.c:1456
netif_change_tx_queue_len+0x179/0x280 net/core/dev.c:9994
do_setlink+0x112d/0x4590 net/core/rtnetlink.c:3203
rtnl_group_changelink net/core/rtnetlink.c:3812 [inline]
__rtnl_newlink net/core/rtnetlink.c:3980 [inline]
rtnl_newlink+0x14ca/0x1bb0 net/core/rtnetlink.c:4108
rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:6994
netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x80f/0x9b0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:721 [inline]
__sock_sendmsg net/socket.c:736 [inline]
____sys_sendmsg+0x972/0x9f0 net/socket.c:2585
___sys_sendmsg+0x2a5/0x360 net/socket.c:2639
__sys_sendmsg net/socket.c:2671 [inline]
__do_sys_sendmsg net/socket.c:2676 [inline]
__se_sys_sendmsg net/socket.c:2674 [inline]
__x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2674
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f86a999c819
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:00007f86a7791028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f86a9c16270 RCX: 00007f86a999c819
RDX: 0000000000000000 RSI: 0000200000000040 RDI: 000000000000000a
RBP: 00007f86a9a32c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f86a9c16308 R14: 00007f86a9c16270 R15: 00007ffd2f825ca8
Allocated by task 11295:
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/0x660 mm/slub.c:5380
kmalloc_noprof include/linux/slab.h:950 [inline]
kzalloc_noprof include/linux/slab.h:1188 [inline]
ax25_dev_device_up+0x54/0x5f0 net/ax25/ax25_dev.c:57
ax25_device_event+0x127/0x8a0 net/ax25/af_ax25.c:143
notifier_call_chain+0x1be/0x400 kernel/notifier.c:85
call_netdevice_notifiers_extack net/core/dev.c:2293 [inline]
call_netdevice_notifiers net/core/dev.c:2307 [inline]
__dev_notify_flags+0x1a9/0x310 net/core/dev.c:9854
netif_change_flags+0xe8/0x1a0 net/core/dev.c:9883
dev_change_flags+0x130/0x260 net/core/dev_api.c:68
dev_ioctl+0x7b4/0x1150 net/core/dev_ioctl.c:814
sock_do_ioctl+0x23e/0x320 net/socket.c:1261
sock_ioctl+0x5c6/0x7f0 net/socket.c:1368
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 14346:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
kasan_save_free_info+0x46/0x50 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:2685 [inline]
__rcu_free_sheaf_prepare+0x129/0x290 mm/slub.c:2954
rcu_free_sheaf+0x31/0x200 mm/slub.c:5811
rcu_do_batch kernel/rcu/tree.c:2617 [inline]
rcu_core+0x7cd/0x1070 kernel/rcu/tree.c:2869
handle_softirqs+0x22a/0x870 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0x5f/0x150 kernel/softirq.c:723
irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1056
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
The buggy address belongs to the object at ffff888035f08000
which belongs to the cache kmalloc-256 of size 256
The buggy address is located 96 bytes inside of
freed 256-byte region [ffff888035f08000, ffff888035f08100)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x35f08
head: order:1 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 ffff88813fea7b40 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88813fea7b40 dead000000000100 dead000000000122
head: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
head: 00fff00000000001 ffffea0000d7c201 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5865, tgid 5865 (syz-executor), ts 335980594772, free_ts 335864092175
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
prep_new_page mm/page_alloc.c:1897 [inline]
get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
__alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
alloc_slab_page mm/slub.c:3292 [inline]
allocate_slab+0x77/0x660 mm/slub.c:3481
new_slab mm/slub.c:3539 [inline]
refill_objects+0x331/0x3c0 mm/slub.c:7175
refill_sheaf mm/slub.c:2812 [inline]
__pcs_replace_empty_main+0x2e6/0x730 mm/slub.c:4615
alloc_from_pcs mm/slub.c:4717 [inline]
slab_alloc_node mm/slub.c:4851 [inline]
__do_kmalloc_node mm/slub.c:5259 [inline]
__kmalloc_noprof+0x474/0x760 mm/slub.c:5272
kmalloc_noprof include/linux/slab.h:954 [inline]
kzalloc_noprof include/linux/slab.h:1188 [inline]
new_dir fs/proc/proc_sysctl.c:966 [inline]
get_subdir fs/proc/proc_sysctl.c:1010 [inline]
sysctl_mkdir_p fs/proc/proc_sysctl.c:1320 [inline]
__register_sysctl_table+0xba1/0x1340 fs/proc/proc_sysctl.c:1395
__devinet_sysctl_register+0x386/0x490 net/ipv4/devinet.c:2712
devinet_sysctl_register+0x187/0x200 net/ipv4/devinet.c:2752
inetdev_event+0xf35/0x1610 net/ipv4/devinet.c:1664
notifier_call_chain+0x1be/0x400 kernel/notifier.c:85
call_netdevice_notifiers_extack net/core/dev.c:2293 [inline]
call_netdevice_notifiers net/core/dev.c:2307 [inline]
netif_change_name+0x5e5/0x960 net/core/dev.c:1515
do_setlink+0xb6c/0x4590 net/core/rtnetlink.c:3160
rtnl_changelink net/core/rtnetlink.c:3798 [inline]
__rtnl_newlink net/core/rtnetlink.c:3971 [inline]
rtnl_newlink+0x15ad/0x1bb0 net/core/rtnetlink.c:4108
rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:6994
page last free pid 5868 tgid 5868 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1433 [inline]
__free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978
__slab_free+0x263/0x2b0 mm/slub.c:5573
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x97/0x100 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:4538 [inline]
slab_alloc_node mm/slub.c:4866 [inline]
__kmalloc_cache_noprof+0x2ba/0x660 mm/slub.c:5375
kmalloc_noprof include/linux/slab.h:950 [inline]
netdevice_queue_work drivers/infiniband/core/roce_gid_mgmt.c:663 [inline]
netdevice_event+0x3cb/0x8f0 drivers/infiniband/core/roce_gid_mgmt.c:822
notifier_call_chain+0x1be/0x400 kernel/notifier.c:85
call_netdevice_notifiers_extack net/core/dev.c:2293 [inline]
call_netdevice_notifiers net/core/dev.c:2307 [inline]
netif_set_mac_address+0x39f/0x4e0 net/core/dev.c:10056
do_setlink+0x9b1/0x4590 net/core/rtnetlink.c:3132
rtnl_changelink net/core/rtnetlink.c:3798 [inline]
__rtnl_newlink net/core/rtnetlink.c:3971 [inline]
rtnl_newlink+0x15ad/0x1bb0 net/core/rtnetlink.c:4108
rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:6994
netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x80f/0x9b0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:721 [inline]
__sock_sendmsg net/socket.c:736 [inline]
__sys_sendto+0x672/0x710 net/socket.c:2199
Memory state around the buggy address:
ffff888035f07f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff888035f07f80: 00 00 00 00 00 00 00 06 fc fc fc fc fc fc fc fc
>ffff888035f08000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888035f08080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888035f08100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
----------------
Code disassembly (best guess):
0: f7 e8 imul %eax
2: fd std
3: cc int3
4: ec in (%dx),%al
5: f5 cmc
6: f7 c3 00 02 00 00 test $0x200,%ebx
c: 74 05 je 0x13
e: e8 90 38 18 f6 call 0xf61838a3
13: 9c pushf
14: 58 pop %rax
15: a9 00 02 00 00 test $0x200,%eax
1a: 75 27 jne 0x43
1c: f7 c3 00 02 00 00 test $0x200,%ebx
22: 74 01 je 0x25
24: fb sti
25: bf 01 00 00 00 mov $0x1,%edi
* 2a: e8 e4 87 de f5 call 0xf5de8813 <-- trapping instruction
2f: 65 8b 05 0d c0 67 07 mov %gs:0x767c00d(%rip),%eax # 0x767c043
36: 85 c0 test %eax,%eax
38: 74 18 je 0x52
3a: 5b pop %rbx
3b: 41 5e pop %r14
3d: c3 ret
3e: cc int3
3f: cc int3