From: syzbot <syzbot+f8a0f50ead274d8516d3@syzkaller.appspotmail.com>
To: bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com,
jeffinphilip14@gmail.com, linux-kernel@vger.kernel.org,
linux-usb@vger.kernel.org, mingo@redhat.com,
syzkaller-bugs@googlegroups.com, tglx@kernel.org,
x86@kernel.org
Subject: Re: [syzbot] [usb?] KASAN: slab-use-after-free Read in atkbd_event_work
Date: Mon, 14 Sep 2026 20:21:40 -0700 [thread overview]
Message-ID: <6aa8b9c4.f81106d8.2ab401.005d.GAE@google.com> (raw)
In-Reply-To: <6a923059.1d9ded08.62e62.00fa.GAE@google.com>
syzbot has found a reproducer for the following issue on:
HEAD commit: 704340f1cd0d Merge tag 'x86_urgent_for_7.3-rc4' of git://g..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1318a115580000
kernel config: https://syzkaller.appspot.com/x/.config?x=5e4e3a0e188a497e
dashboard link: https://syzkaller.appspot.com/bug?extid=f8a0f50ead274d8516d3
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1718a115580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=129c5925580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/020eba5164c7/disk-704340f1.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c1203c300bbc/vmlinux-704340f1.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7378e6cf5c10/bzImage-704340f1.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f8a0f50ead274d8516d3@syzkaller.appspotmail.com
==================================================================
BUG: KASAN: slab-use-after-free in atkbd_event_work+0x592/0x650 drivers/input/keyboard/atkbd.c:-1
Read of size 4 at addr ffff88807f924164 by task kworker/0:1/10
CPU: 0 UID: 0 PID: 10 Comm: kworker/0:1 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/05/2026
Workqueue: events atkbd_event_work
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_address_description+0x55/0x1e0 mm/kasan/report.c:378
print_report+0x58/0x70 mm/kasan/report.c:482
kasan_report+0x117/0x150 mm/kasan/report.c:595
atkbd_event_work+0x592/0x650 drivers/input/keyboard/atkbd.c:-1
process_one_work kernel/workqueue.c:3396 [inline]
process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479
worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560
kthread+0x38b/0x480 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
Allocated by task 9:
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+0x321/0x600 mm/slub.c:5563
_kmalloc_noprof include/linux/slab.h:991 [inline]
_kzalloc_noprof include/linux/slab.h:1312 [inline]
input_allocate_device+0x4e/0x2a0 drivers/input/input.c:1960
atkbd_connect+0xb1/0x9c0 drivers/input/keyboard/atkbd.c:1258
serio_connect_driver drivers/input/serio/serio.c:44 [inline]
serio_driver_probe+0x82/0xa0 drivers/input/serio/serio.c:748
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x254/0xae0 drivers/base/dd.c:706
__driver_probe_device+0x1e8/0x360 drivers/base/dd.c:868
driver_probe_device+0x4f/0x240 drivers/base/dd.c:898
__device_attach_driver+0x270/0x410 drivers/base/dd.c:1026
bus_for_each_drv+0x258/0x2f0 drivers/base/bus.c:500
__device_attach+0x2c4/0x450 drivers/base/dd.c:1098
device_initial_probe+0xa1/0xd0 drivers/base/dd.c:1153
bus_probe_device+0x12a/0x220 drivers/base/bus.c:620
device_add+0x7d7/0xb80 drivers/base/core.c:3776
serio_add_port drivers/input/serio/serio.c:512 [inline]
serio_handle_event+0x9e6/0xf80 drivers/input/serio/serio.c:197
process_one_work kernel/workqueue.c:3396 [inline]
process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479
worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560
kthread+0x38b/0x480 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Freed by task 5639:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
kasan_save_free_info+0x40/0x50 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:2748 [inline]
slab_free mm/slub.c:6508 [inline]
kfree+0x1c5/0x650 mm/slub.c:6801
input_dev_release+0xab/0xc0 drivers/input/input.c:1644
device_release+0xc4/0x1f0 drivers/base/core.c:-1
kobject_cleanup lib/kobject.c:689 [inline]
kobject_release lib/kobject.c:720 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x222/0x550 lib/kobject.c:737
atkbd_disconnect+0xb5/0x110 drivers/input/keyboard/atkbd.c:966
serio_disconnect_driver drivers/input/serio/serio.c:62 [inline]
serio_driver_remove+0x85/0xa0 drivers/input/serio/serio.c:755
device_remove drivers/base/dd.c:616 [inline]
__device_release_driver drivers/base/dd.c:1349 [inline]
device_release_driver_internal+0x48b/0x880 drivers/base/dd.c:1372
serio_disconnect_port drivers/input/serio/serio.c:646 [inline]
serio_unregister_port+0x128/0x150 drivers/input/serio/serio.c:679
userio_char_release+0x80/0xc0 drivers/input/serio/userio.c:105
__fput+0x418/0xa50 fs/file_table.c:512
task_work_run+0x1d9/0x270 kernel/task_work.c:233
exit_task_work include/linux/task_work.h:40 [inline]
do_exit+0x73a/0x2360 kernel/exit.c:1011
do_group_exit+0x22d/0x2f0 kernel/exit.c:1154
__do_sys_exit_group kernel/exit.c:1165 [inline]
__se_sys_exit_group kernel/exit.c:1163 [inline]
__x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1163
x64_sys_call+0x18c6/0x18d0 arch/x86/include/generated/asm/syscalls_64.h:232
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
The buggy address belongs to the object at ffff88807f924000
which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 356 bytes inside of
freed 4096-byte region [ffff88807f924000, ffff88807f925000)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7f920
head: order:3 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 ffff88801b042140 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801b042140 dead000000000100 dead000000000122
head: 0000000000000000 0000000000040004 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 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 4982, tgid 4982 (udevd), ts 43635359949
set_page_owner include/linux/page_owner.h:33 [inline]
post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1871
prep_new_page mm/page_alloc.c:1879 [inline]
get_page_from_freelist+0x2209/0x2280 mm/page_alloc.c:3943
__alloc_frozen_pages_noprof+0x217/0x5a0 mm/page_alloc.c:5436
alloc_slab_page mm/slub.c:3347 [inline]
allocate_slab+0x7d/0x620 mm/slub.c:3462
new_slab mm/slub.c:3513 [inline]
refill_objects+0x2d5/0x350 mm/slub.c:7417
refill_sheaf mm/slub.c:2885 [inline]
__pcs_replace_empty_main+0x2c8/0x6c0 mm/slub.c:4774
alloc_from_pcs mm/slub.c:4850 [inline]
slab_alloc_node mm/slub.c:4984 [inline]
__do_kmalloc_node mm/slub.c:5413 [inline]
__kmalloc_noprof+0x47b/0x720 mm/slub.c:5439
_kmalloc_noprof include/linux/slab.h:995 [inline]
tomoyo_realpath_from_path+0xef/0x640 security/tomoyo/realpath.c:251
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_check_open_permission+0x229/0x470 security/tomoyo/file.c:776
security_file_open+0xa9/0x240 security/security.c:2739
do_dentry_open+0x4a0/0x1380 fs/open.c:973
vfs_open+0x3b/0x340 fs/open.c:1101
do_open fs/namei.c:4837 [inline]
path_openat+0x1443/0x1d60 fs/namei.c:5000
do_file_open+0x23e/0x4a0 fs/namei.c:5029
do_sys_openat2+0x115/0x200 fs/open.c:1417
do_sys_open fs/open.c:1423 [inline]
__do_sys_openat fs/open.c:1439 [inline]
__se_sys_openat fs/open.c:1434 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1434
page last free pid 4985 tgid 4985 ts 43408573557 stack trace:
reset_page_owner include/linux/page_owner.h:26 [inline]
__free_pages_prepare mm/page_alloc.c:1418 [inline]
__free_frozen_pages+0xc93/0xd90 mm/page_alloc.c:2962
__slab_free+0x274/0x2c0 mm/slub.c:5823
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x99/0x100 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:4683 [inline]
slab_alloc_node mm/slub.c:4996 [inline]
__kmalloc_cache_noprof+0x29f/0x600 mm/slub.c:5559
_kmalloc_noprof include/linux/slab.h:991 [inline]
_kzalloc_noprof include/linux/slab.h:1312 [inline]
kernfs_fop_open+0x3ac/0xce0 fs/kernfs/file.c:634
do_dentry_open+0x816/0x1380 fs/open.c:996
vfs_open+0x3b/0x340 fs/open.c:1101
do_open fs/namei.c:4837 [inline]
path_openat+0x1443/0x1d60 fs/namei.c:5000
do_file_open+0x23e/0x4a0 fs/namei.c:5029
do_sys_openat2+0x115/0x200 fs/open.c:1417
do_sys_open fs/open.c:1423 [inline]
__do_sys_openat fs/open.c:1439 [inline]
__se_sys_openat fs/open.c:1434 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1434
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Memory state around the buggy address:
ffff88807f924000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807f924080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88807f924100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88807f924180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807f924200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
next prev parent reply other threads:[~2026-09-15 3:21 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-29 1:05 [syzbot] [kernel?] " syzbot
2026-08-29 4:54 ` Jeffin Philip
2026-09-15 3:21 ` syzbot [this message]
2026-09-15 9:24 ` [syzbot] [usb?] " Edward Adam Davis
2026-09-15 12:02 ` syzbot
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