==================================================================
BUG: KASAN: slab-use-after-free in ax25_heartbeat_expiry+0x115/0x140 net/ax25/ax25_timer.c:127
Read of size 4 at addr ffff88802845d660 by task syz.0.3049/17341
CPU: 1 UID: 0 PID: 17341 Comm: syz.0.3049 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
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:check_kcov_mode kernel/kcov.c:183 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:246 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp8+0x17/0x90 kernel/kcov.c:321
Code: 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 04 24 65 48 8b 0d 18 6a 56 11 65 8b 15 39 6a 56 11 <81> e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 57 83 b9 a4 16 00 00
RSP: 0018:ffffc90003027378 EFLAGS: 00000246
RAX: ffffffff81784e61 RBX: 80000000932fc007 RCX: ffff888029543d00
RDX: 0000000080000001 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90003027670 R08: ffffea00024cbf07 R09: 1ffffd40004997e0
R10: dffffc0000000000 R11: fffff940004997e1 R12: 1ffffd40004997e3
R13: dffffc0000000000 R14: 00000000180400fb R15: 0000002000000000
arch_check_zapped_pte+0x51/0xb0 arch/x86/mm/pgtable.c:831
zap_present_folio_ptes mm/memory.c:1660 [inline]
zap_present_ptes mm/memory.c:1725 [inline]
do_zap_pte_range mm/memory.c:1827 [inline]
zap_pte_range mm/memory.c:1929 [inline]
zap_pmd_range mm/memory.c:2021 [inline]
zap_pud_range mm/memory.c:2049 [inline]
zap_p4d_range mm/memory.c:2070 [inline]
unmap_page_range+0x1b4c/0x48f0 mm/memory.c:2091
unmap_single_vma mm/memory.c:2133 [inline]
unmap_vmas+0x48f/0x6a0 mm/memory.c:2171
exit_mmap+0x280/0xa10 mm/mmap.c:1302
__mmput+0x118/0x430 kernel/fork.c:1175
exit_mm+0x168/0x220 kernel/exit.c:581
do_exit+0x6a2/0x23c0 kernel/exit.c:964
do_group_exit+0x21b/0x2d0 kernel/exit.c:1118
get_signal+0x1284/0x1330 kernel/signal.c:3034
arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
exit_to_user_mode_loop+0x86/0x480 kernel/entry/common.c:98
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f79e779c799
Code: Unable to access opcode bytes at 0x7f79e779c76f.
RSP: 002b:00007f79e87120e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: 0000000000000001 RBX: 00007f79e7a16098 RCX: 00007f79e779c799
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f79e7a1609c
RBP: 00007f79e7a16090 R08: 3fffffffffffffff R09: 0000000000000000
R10: 000000000000059a R11: 0000000000000246 R12: 0000000000000000
R13: 00007f79e7a16128 R14: 00007ffee08e9490 R15: 00007ffee08e9578
Allocated by task 14099:
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:2288 [inline]
call_netdevice_notifiers net/core/dev.c:2302 [inline]
__dev_notify_flags+0x1a9/0x310 net/core/dev.c:9821
netif_change_flags+0xe8/0x1a0 net/core/dev.c:9850
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 3:
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 ffff88802845d600
which belongs to the cache kmalloc-256 of size 256
The buggy address is located 96 bytes inside of
freed 256-byte region [ffff88802845d600, ffff88802845d700)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2845c
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 ffff88813fea5b40 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88813fea5b40 dead000000000100 dead000000000122
head: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
head: 00fff00000000001 ffffea0000a11701 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 1, tgid 1 (swapper/0), ts 8016777620, free_ts 0
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]
__kmalloc_cache_noprof+0x392/0x660 mm/slub.c:5375
kmalloc_noprof include/linux/slab.h:950 [inline]
kzalloc_noprof include/linux/slab.h:1188 [inline]
bus_add_driver+0x162/0x670 drivers/base/bus.c:699
driver_register+0x23a/0x320 drivers/base/driver.c:249
usb_register_driver+0x1e4/0x390 drivers/usb/core/driver.c:1078
do_one_initcall+0x250/0x8d0 init/main.c:1382
do_initcall_level+0x104/0x190 init/main.c:1444
do_initcalls+0x59/0xa0 init/main.c:1460
kernel_init_freeable+0x2a6/0x3e0 init/main.c:1692
kernel_init+0x1d/0x1d0 init/main.c:1582
ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
page_owner free stack trace missing
Memory state around the buggy address:
ffff88802845d500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88802845d580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88802845d600: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88802845d680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802845d700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
----------------
Code disassembly (best guess):
0: 00 00 add %al,(%rax)
2: 00 90 90 90 90 90 add %dl,-0x6f6f6f70(%rax)
8: 90 nop
9: 90 nop
a: 90 nop
b: 90 nop
c: 90 nop
d: 90 nop
e: 90 nop
f: 90 nop
10: 90 nop
11: 90 nop
12: 90 nop
13: f3 0f 1e fa endbr64
17: 48 8b 04 24 mov (%rsp),%rax
1b: 65 48 8b 0d 18 6a 56 mov %gs:0x11566a18(%rip),%rcx # 0x11566a3b
22: 11
23: 65 8b 15 39 6a 56 11 mov %gs:0x11566a39(%rip),%edx # 0x11566a63
* 2a: 81 e2 00 01 ff 00 and $0xff0100,%edx <-- trapping instruction
30: 74 11 je 0x43
32: 81 fa 00 01 00 00 cmp $0x100,%edx
38: 75 57 jne 0x91
3a: 83 .byte 0x83
3b: b9 a4 16 00 00 mov $0x16a4,%ecx