KASAN: slab-use-after-free Read in atkbd_set_repeat_rate

Status: upstream: reported C repro on 2026/08/28 00:44
Subsystems: input
Labels: prio:high actionable
[Documentation on labels]
Reported-by: syzbot+1e2ef9bcb29af666b2e6@syzkaller.appspotmail.com
First crash: 4d18h, last: 3h01m
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
7862cad1 moderation Actionable: ✅ ❓ KASAN: slab-use-after-free Read in atkbd_set_repeat_rate 2026/08/28 00:01 2026/08/28 00:01 2026/08/28 00:43 bd6de8ec
a38db519 assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ✅ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ✅ ❓ KASAN: slab-use-after-free Read in atkbd_set_repeat_rate 2026/08/25 00:29 2026/08/25 00:29 2026/08/25 00:38 23caa175
▶ ▼ Discussions (3)
Title Replies (including bot) Last reply
[PATCH v2] Input: atkbd - fix UAF in atkbd_set_repeat_rate() on disconnect 2 (2) 2026/08/28 14:32
[syzbot] [input?] KASAN: slab-use-after-free Read in atkbd_set_repeat_rate 3 (8) 2026/08/28 14:20
[PATCH] Input: atkbd - fix UAF in atkbd_set_repeat_rate() on disconnect 1 (1) 2026/08/28 08:08
▶ ▼ Last patch testing requests (3)
Created Duration User Patch Repo Result
2026/08/28 14:03 14m jeffinphilip14@gmail.com patch git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 818bebeb63dd OK job log log
2026/08/28 13:42 14m jeffinphilip14@gmail.com patch git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 818bebeb63dd OK job log log
2026/08/28 12:54 7m jeffinphilip14@gmail.com patch git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 818bebeb63dd error job log

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in atkbd_set_repeat_rate.isra.0+0x44a/0x4e0 drivers/input/keyboard/atkbd.c:578
Read of size 4 at addr ffff888036712164 by task kworker/1:2/850

CPU: 1 UID: 0 PID: 850 Comm: kworker/1:2 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Workqueue: events atkbd_event_work
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x13d/0x4b0 mm/kasan/report.c:482
 kasan_report+0xdf/0x1c0 mm/kasan/report.c:595
 atkbd_set_repeat_rate.isra.0+0x44a/0x4e0 drivers/input/keyboard/atkbd.c:578
 atkbd_event_work+0x12c/0x160 drivers/input/keyboard/atkbd.c:640
 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3387
 process_scheduled_works kernel/workqueue.c:3470 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3551
 kthread+0x373/0x450 kernel/kthread.c:436
 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 29:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x2e7/0x6b0 mm/slub.c:5484
 _kmalloc_noprof include/linux/slab.h:988 [inline]
 _kzalloc_noprof include/linux/slab.h:1309 [inline]
 input_allocate_device+0x44/0x350 drivers/input/input.c:1960
 atkbd_connect+0x9e/0x9c0 drivers/input/keyboard/atkbd.c:1258
 serio_connect_driver drivers/input/serio/serio.c:44 [inline]
 serio_driver_probe+0x77/0xa0 drivers/input/serio/serio.c:748
 call_driver_probe drivers/base/dd.c:628 [inline]
 really_probe+0x241/0xa60 drivers/base/dd.c:706
 __driver_probe_device+0x210/0x460 drivers/base/dd.c:868
 driver_probe_device+0x4a/0x140 drivers/base/dd.c:898
 __device_attach_driver+0x1df/0x320 drivers/base/dd.c:1026
 bus_for_each_drv+0x159/0x1e0 drivers/base/bus.c:500
 __device_attach+0x1e4/0x4d0 drivers/base/dd.c:1098
 device_initial_probe+0xaf/0xd0 drivers/base/dd.c:1153
 bus_probe_device+0x64/0x160 drivers/base/bus.c:620
 device_add+0x121d/0x1970 drivers/base/core.c:3776
 serio_add_port drivers/input/serio/serio.c:512 [inline]
 serio_handle_event+0x593/0x970 drivers/input/serio/serio.c:197
 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3387
 process_scheduled_works kernel/workqueue.c:3470 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3551
 kthread+0x373/0x450 kernel/kthread.c:436
 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 6032:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2678 [inline]
 slab_free mm/slub.c:6372 [inline]
 kfree+0x22b/0x6c0 mm/slub.c:6687
 input_dev_release+0xab/0xd0 drivers/input/input.c:1644
 device_release+0xd2/0x270 drivers/base/core.c:2640
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x1f7/0x640 lib/kobject.c:737
 put_device+0x1f/0x30 drivers/base/core.c:3884
 input_put_device include/linux/input.h:391 [inline]
 input_unregister_device+0xd8/0x110 drivers/input/input.c:2492
 atkbd_disconnect+0xcb/0x150 drivers/input/keyboard/atkbd.c:966
 serio_disconnect_driver drivers/input/serio/serio.c:62 [inline]
 serio_driver_remove+0x7b/0xa0 drivers/input/serio/serio.c:755
 device_remove+0xcb/0x180 drivers/base/dd.c:616
 __device_release_driver drivers/base/dd.c:1349 [inline]
 device_release_driver_internal+0x44e/0x620 drivers/base/dd.c:1372
 serio_unregister_port+0x23/0x40 drivers/input/serio/serio.c:679
 userio_char_release+0x91/0xe0 drivers/input/serio/userio.c:105
 __fput+0x3ff/0xb50 fs/file_table.c:512
 fput_close_sync+0x118/0x250 fs/file_table.c:617
 __do_sys_close fs/open.c:1560 [inline]
 __se_sys_close fs/open.c:1545 [inline]
 __x64_sys_close+0x8b/0x120 fs/open.c:1545
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888036712000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 356 bytes inside of
 freed 4096-byte region [ffff888036712000, ffff888036713000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x36710
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 ffff88801c043040 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800040004 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801c043040 dead000000000100 dead000000000122
head: 0000000000000000 0000000800040004 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 5138, tgid 5138 (udevd), ts 23156728902
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1871
 prep_new_page mm/page_alloc.c:1879 [inline]
 get_page_from_freelist+0x110d/0x35b0 mm/page_alloc.c:3943
 __alloc_frozen_pages_noprof+0x2eb/0x3300 mm/page_alloc.c:5436
 alloc_slab_page mm/slub.c:3267 [inline]
 allocate_slab mm/slub.c:3382 [inline]
 new_slab+0xa5/0x640 mm/slub.c:3428
 refill_objects+0xe3/0x410 mm/slub.c:7305
 refill_sheaf mm/slub.c:2805 [inline]
 __pcs_replace_empty_main+0x372/0x680 mm/slub.c:4677
 alloc_from_pcs mm/slub.c:4775 [inline]
 slab_alloc_node mm/slub.c:4907 [inline]
 __do_kmalloc_node mm/slub.c:5336 [inline]
 __kmalloc_noprof+0x66b/0x820 mm/slub.c:5362
 _kmalloc_noprof include/linux/slab.h:992 [inline]
 tomoyo_realpath_from_path+0xb6/0x690 security/tomoyo/realpath.c:251
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_check_open_permission+0x2af/0x3c0 security/tomoyo/file.c:776
 tomoyo_file_open+0x6b/0x90 security/tomoyo/tomoyo.c:334
 security_file_open+0xb5/0x1e0 security/security.c:2739
 do_dentry_open+0x588/0x14d0 fs/open.c:973
 vfs_open+0x82/0x3f0 fs/open.c:1101
 do_open fs/namei.c:4837 [inline]
 path_openat+0x19fa/0x2440 fs/namei.c:5000
 do_file_open+0x20e/0x430 fs/namei.c:5029
 do_sys_openat2+0x10f/0x1e0 fs/open.c:1417
page last free pid 5139 tgid 5139 ts 23149284278 stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 __free_pages_prepare mm/page_alloc.c:1418 [inline]
 __free_frozen_pages+0x79f/0x10f0 mm/page_alloc.c:2962
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x47/0xf0 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4586 [inline]
 slab_alloc_node mm/slub.c:4919 [inline]
 kmem_cache_alloc_noprof+0x26b/0x6a0 mm/slub.c:4933
 alloc_empty_file+0x5b/0x1c0 fs/file_table.c:262
 path_openat+0xdb/0x2440 fs/namei.c:4986
 do_file_open+0x20e/0x430 fs/namei.c:5029
 do_sys_openat2+0x10f/0x1e0 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+0x12d/0x210 fs/open.c:1434
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888036712000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888036712080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888036712100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff888036712180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888036712200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/28 11:41 git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 818bebeb63dd 614e416a .config console log report C ci-qemu-upstream KASAN: slab-use-after-free Read in atkbd_set_repeat_rate
2026/08/25 05:37 upstream 66498c75b4f8 23caa175 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root KASAN: slab-use-after-free Read in atkbd_set_repeat_rate
2026/08/23 19:53 upstream 818bebeb63dd 1e72964b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: slab-use-after-free Read in atkbd_set_repeat_rate
* Struck through repros no longer work on HEAD.