==================================================================
BUG: KASAN: use-after-free in ax25_t1timer_expiry+0xec/0x110 net/ax25/ax25_timer.c:148
Read of size 4 at addr ffff88814b169c50 by task syz.1.394/5673
CPU: 1 PID: 5673 Comm: syz.1.394 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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_t1timer_expiry+0xec/0x110 net/ax25/ax25_timer.c:148
call_timer_fn+0x17b/0x540 kernel/time/timer.c:1451
expire_timers kernel/time/timer.c:1496 [inline]
__run_timers+0x53a/0x7f0 kernel/time/timer.c:1767
run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1780
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:__sanitizer_cov_trace_cmp8+0x7a/0x80 kernel/kcov.c:274
Code: c1 e0 05 4d 8d 50 28 4d 39 ca 77 1e 4a c7 44 02 08 06 00 00 00 4a 89 7c 02 10 4a 89 74 02 18 4a 89 44 02 20 48 ff c1 48 89 0a 0f 1f 44 00 00 48 8b 04 24 65 48 8b 0d b4 4d 89 7e 65 8b 15 b5
RSP: 0018:ffffc9000447f9c0 EFLAGS: 00000293
RAX: ffffffff81ad9f85 RBX: 00007f11a9824000 RCX: ffff888028878000
RDX: 0000000000000000 RSI: 00007f11a9c24000 RDI: 00007f11a9824000
RBP: 1ffff11014aaa00a R08: 0000000000000000 R09: 1ffff1100e84fc6c
R10: dffffc0000000000 R11: ffffed100e84fc6d R12: 00007f11a9c24000
R13: 0000000000000000 R14: ffff8880a5550000 R15: ffff8880a5550050
unmap_single_vma+0x135/0x2b0 mm/memory.c:1602
unmap_vmas+0x131/0x250 mm/memory.c:1653
exit_mmap+0x3b9/0x640 mm/mmap.c:3216
__mmput+0x115/0x3b0 kernel/fork.c:1127
exit_mm+0x588/0x6e0 kernel/exit.c:550
do_exit+0x5a9/0x20c0 kernel/exit.c:870
do_group_exit+0x12e/0x300 kernel/exit.c:997
__do_sys_exit_group kernel/exit.c:1008 [inline]
__se_sys_exit_group kernel/exit.c:1006 [inline]
__x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1006
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: 0033:0x7f11aa1c1eb9
Code: Unable to access opcode bytes at RIP 0x7f11aa1c1e8f.
RSP: 002b:00007ffddc5180b8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f11aa1c1eb9
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffddc51811c R08: 0000000000000000 R09: 000055558f0269f0
R10: 0000000000000001 R11: 0000000000000246 R12: 000000000000004c
R13: 000055558f0269f0 R14: 000000000002d438 R15: 00007ffddc518170
Allocated by task 5523:
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:2061 [inline]
call_netdevice_notifiers net/core/dev.c:2075 [inline]
__dev_notify_flags+0x194/0x300 net/core/dev.c:8891
dev_change_flags+0xe3/0x1a0 net/core/dev.c:8929
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 5663:
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
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181
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
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x66/0xd0
Last potentially related work creation:
kasan_save_stack+0x35/0x60 mm/kasan/common.c:38
kasan_record_aux_stack+0xb8/0x100 mm/kasan/generic.c:348
insert_work+0x54/0x3d0 kernel/workqueue.c:1366
__queue_work+0x9c5/0xd50 kernel/workqueue.c:1532
queue_work_on+0x124/0x1f0 kernel/workqueue.c:1559
queue_work include/linux/workqueue.h:512 [inline]
call_usermodehelper_exec+0x2e3/0x520 kernel/umh.c:435
kobject_uevent_env+0x681/0x890 lib/kobject_uevent.c:633
device_add+0x91c/0xfb0 drivers/base/core.c:3393
__video_register_device+0x38fd/0x4670 drivers/media/v4l2-core/v4l2-dev.c:1042
video_register_device include/media/v4l2-dev.h:384 [inline]
vivid_create_devnodes+0x1453/0x2cd0 drivers/media/test-drivers/vivid/vivid-core.c:1566
vivid_create_instance drivers/media/test-drivers/vivid/vivid-core.c:1976 [inline]
vivid_probe+0x4f45/0x67a0 drivers/media/test-drivers/vivid/vivid-core.c:2031
platform_probe+0x137/0x1c0 drivers/base/platform.c:1391
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x284/0xc80 drivers/base/dd.c:595
__driver_probe_device+0x18c/0x330 drivers/base/dd.c:755
driver_probe_device+0x4f/0x420 drivers/base/dd.c:785
__driver_attach+0x46b/0x670 drivers/base/dd.c:1164
bus_for_each_dev+0x182/0x1f0 drivers/base/bus.c:303
bus_add_driver+0x30a/0x5a0 drivers/base/bus.c:620
driver_register+0x32d/0x430 drivers/base/driver.c:240
vivid_init+0x39/0x70 drivers/media/test-drivers/vivid/vivid-core.c:2161
do_one_initcall+0x272/0x730 init/main.c:1316
do_initcall_level+0x137/0x1f0 init/main.c:1389
do_initcalls+0x4b/0x90 init/main.c:1405
kernel_init_freeable+0x3e9/0x570 init/main.c:1629
kernel_init+0x19/0x1b0 init/main.c:1520
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
The buggy address belongs to the object at ffff88814b169c00
which belongs to the cache kmalloc-192 of size 192
The buggy address is located 80 bytes inside of
192-byte region [ffff88814b169c00, ffff88814b169cc0)
The buggy address belongs to the page:
page:ffffea00052c5a40 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88814b169700 pfn:0x14b169
flags: 0x57ff00000000200(slab|node=1|zone=2|lastcpupid=0x7ff)
raw: 057ff00000000200 ffffea00052076c8 ffffea0005223e88 ffff888016c41a00
raw: ffff88814b169700 0000000000100009 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 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 1, ts 9119577759, free_ts 0
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:5487
alloc_page_interleave+0x24/0x1e0 mm/mempolicy.c:2031
alloc_slab_page mm/slub.c:1780 [inline]
allocate_slab mm/slub.c:1917 [inline]
new_slab+0xc0/0x4b0 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]
slab_alloc mm/slub.c:3233 [inline]
kmem_cache_alloc_trace+0x1a5/0x2a0 mm/slub.c:3250
kmalloc include/linux/slab.h:607 [inline]
kzalloc include/linux/slab.h:738 [inline]
call_usermodehelper_setup+0x8a/0x260 kernel/umh.c:365
kobject_uevent_env+0x65e/0x890 lib/kobject_uevent.c:629
device_add+0x91c/0xfb0 drivers/base/core.c:3393
__video_register_device+0x38fd/0x4670 drivers/media/v4l2-core/v4l2-dev.c:1042
video_register_device include/media/v4l2-dev.h:384 [inline]
vivid_create_devnodes+0x1397/0x2cd0 drivers/media/test-drivers/vivid/vivid-core.c:1615
vivid_create_instance drivers/media/test-drivers/vivid/vivid-core.c:1976 [inline]
vivid_probe+0x4f45/0x67a0 drivers/media/test-drivers/vivid/vivid-core.c:2031
platform_probe+0x137/0x1c0 drivers/base/platform.c:1391
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x284/0xc80 drivers/base/dd.c:595
__driver_probe_device+0x18c/0x330 drivers/base/dd.c:755
driver_probe_device+0x4f/0x420 drivers/base/dd.c:785
page_owner free stack trace missing
Memory state around the buggy address:
ffff88814b169b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88814b169b80: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
>ffff88814b169c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88814b169c80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff88814b169d00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
0: c1 e0 05 shl $0x5,%eax
3: 4d 8d 50 28 lea 0x28(%r8),%r10
7: 4d 39 ca cmp %r9,%r10
a: 77 1e ja 0x2a
c: 4a c7 44 02 08 06 00 movq $0x6,0x8(%rdx,%r8,1)
13: 00 00
15: 4a 89 7c 02 10 mov %rdi,0x10(%rdx,%r8,1)
1a: 4a 89 74 02 18 mov %rsi,0x18(%rdx,%r8,1)
1f: 4a 89 44 02 20 mov %rax,0x20(%rdx,%r8,1)
24: 48 ff c1 inc %rcx
27: 48 89 0a mov %rcx,(%rdx)
* 2a: c3 ret <-- trapping instruction
2b: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
30: 48 8b 04 24 mov (%rsp),%rax
34: 65 48 8b 0d b4 4d 89 mov %gs:0x7e894db4(%rip),%rcx # 0x7e894df0
3b: 7e
3c: 65 gs
3d: 8b .byte 0x8b
3e: 15 .byte 0x15
3f: b5 .byte 0xb5