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

Status: moderation: reported on 2026/10/02 20:00
Subsystems: input
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+0b014b0891a438e3aff7@syzkaller.appspotmail.com
First crash: 4d07h, last: 4d07h
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
f4a7a62c moderation Actionable: ❌ ❓ KASAN: slab-use-after-free Read in input_default_getkeycode 2026/10/03 00:36 2026/10/03 00:36 2026/10/03 01:21 57bbd979
739109f2 assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ✅ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ KASAN: slab-use-after-free Read in input_default_getkeycode 2026/09/30 05:14 2026/09/30 05:14 2026/09/30 07:07 7808aef4

Sample crash report:
UDC core: USB Raw Gadget: couldn't find an available UDC or it's busy
misc raw-gadget: fail, usb_gadget_register_driver returned -16
UDC core: USB Raw Gadget: couldn't find an available UDC or it's busy
misc raw-gadget: fail, usb_gadget_register_driver returned -16
==================================================================
BUG: KASAN: slab-use-after-free in input_fetch_keycode drivers/input/input.c:831 [inline]
BUG: KASAN: slab-use-after-free in input_default_getkeycode+0x4bc/0x520 drivers/input/input.c:858
Read of size 2 at addr ffff88801e3896d8 by task syz.3.412/7330

CPU: 1 UID: 0 PID: 7330 Comm: syz.3.412 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
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
 input_fetch_keycode drivers/input/input.c:831 [inline]
 input_default_getkeycode+0x4bc/0x520 drivers/input/input.c:858
 input_get_keycode+0x57/0x80 drivers/input/input.c:957
 evdev_handle_get_keycode_v2+0xdd/0x170 drivers/input/evdev.c:836
 evdev_do_ioctl+0xd2e/0x1b40 drivers/input/evdev.c:1138
 evdev_ioctl_handler drivers/input/evdev.c:1277 [inline]
 evdev_ioctl+0x16f/0x1a0 drivers/input/evdev.c:1286
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
 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
RIP: 0033:0x7f143639e159
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:00007f1437321028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f1436625fa0 RCX: 00007f143639e159
RDX: 00002000000000c0 RSI: 0000000080284504 RDI: 0000000000000009
RBP: 00007f143643506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1436626038 R14: 00007f1436625fa0 R15: 00007ffc4eb88548
 </TASK>

Allocated by task 7054:
 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]
 __do_kmalloc_node mm/slub.c:5414 [inline]
 __kmalloc_node_track_caller_noprof+0x33d/0x870 mm/slub.c:5545
 kmalloc_reserve+0xe8/0x350 net/core/skbuff.c:637
 pskb_expand_head+0x249/0x10e0 net/core/skbuff.c:2315
 __pskb_pull_tail+0x122/0x18c0 net/core/skbuff.c:2890
 pskb_may_pull_reason include/linux/skbuff.h:2856 [inline]
 pskb_may_pull include/linux/skbuff.h:2865 [inline]
 skb_ensure_writable+0x3c5/0x480 net/core/skbuff.c:6388
 __bpf_try_make_writable net/core/filter.c:1689 [inline]
 sk_skb_try_make_writable net/core/filter.c:1912 [inline]
 ____sk_skb_pull_data net/core/filter.c:1926 [inline]
 sk_skb_pull_data+0x9c/0xd0 net/core/filter.c:1915
 0xffffffffa04007b3
 bpf_dispatcher_nop_func include/linux/bpf.h:1452 [inline]
 __bpf_prog_run include/linux/filter.h:779 [inline]
 bpf_prog_run include/linux/filter.h:786 [inline]
 bpf_prog_run_pin_on_cpu+0xf9/0x4c0 include/linux/filter.h:803
 sk_psock_verdict_recv+0x3f2/0x1480 net/core/skmsg.c:1223
 unix_stream_read_skb+0x32a/0x500 net/unix/af_unix.c:2915
 sk_psock_verdict_data_ready+0x198/0x7c0 net/core/skmsg.c:1251
 unix_stream_sendmsg+0x7cf/0x1310 net/unix/af_unix.c:2499
 sock_sendmsg_nosec net/socket.c:800 [inline]
 __sock_sendmsg net/socket.c:815 [inline]
 ____sys_sendmsg+0xa4d/0xbe0 net/socket.c:2713
 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2767
 __sys_sendmsg+0x160/0x210 net/socket.c:2799
 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

Freed by task 7054:
 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:2748 [inline]
 slab_free mm/slub.c:6508 [inline]
 kfree+0x22b/0x6d0 mm/slub.c:6801
 skb_kfree_head net/core/skbuff.c:1083 [inline]
 skb_free_head+0xb9/0x160 net/core/skbuff.c:1095
 skb_release_data+0x659/0x860 net/core/skbuff.c:1122
 skb_release_all net/core/skbuff.c:1197 [inline]
 __kfree_skb net/core/skbuff.c:1211 [inline]
 sk_skb_reason_drop+0x102/0x1b0 net/core/skbuff.c:1250
 kfree_skb_reason include/linux/skbuff.h:1323 [inline]
 kfree_skb include/linux/skbuff.h:1332 [inline]
 sock_drop include/linux/skmsg.h:330 [inline]
 sk_psock_verdict_apply net/core/skmsg.c:1055 [inline]
 sk_psock_verdict_recv+0x59f/0x1480 net/core/skmsg.c:1226
 unix_stream_read_skb+0x32a/0x500 net/unix/af_unix.c:2915
 sk_psock_verdict_data_ready+0x198/0x7c0 net/core/skmsg.c:1251
 unix_stream_sendmsg+0x7cf/0x1310 net/unix/af_unix.c:2499
 sock_sendmsg_nosec net/socket.c:800 [inline]
 __sock_sendmsg net/socket.c:815 [inline]
 ____sys_sendmsg+0xa4d/0xbe0 net/socket.c:2713
 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2767
 __sys_sendmsg+0x160/0x210 net/socket.c:2799
 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 ffff88801e388000
 which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 5848 bytes inside of
 freed 8192-byte region [ffff88801e388000, ffff88801e38a000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88801e388000 pfn:0x1e388
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000240(workingset|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000240 ffff88801c032280 ffffea0000d13410 ffffea000153ca10
raw: ffff88801e388000 0000000000020001 00000000f5000000 0000000000000000
head: 00fff00000000240 ffff88801c032280 ffffea0000d13410 ffffea000153ca10
head: ffff88801e388000 0000000000020001 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 5308, tgid 5308 (dhcpcd-run-hook), ts 42005874099
 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/0x35d0 mm/page_alloc.c:3943
 __alloc_frozen_pages_noprof+0x2eb/0x3300 mm/page_alloc.c:5436
 alloc_slab_page mm/slub.c:3347 [inline]
 allocate_slab mm/slub.c:3462 [inline]
 new_slab+0xa9/0x6e0 mm/slub.c:3513
 refill_objects+0xe3/0x410 mm/slub.c:7417
 refill_sheaf mm/slub.c:2885 [inline]
 __pcs_replace_empty_main+0x35e/0x650 mm/slub.c:4774
 alloc_from_pcs mm/slub.c:4850 [inline]
 slab_alloc_node mm/slub.c:4984 [inline]
 __kmalloc_cache_noprof+0x4f4/0x6d0 mm/slub.c:5559
 _kmalloc_noprof include/linux/slab.h:991 [inline]
 _kzalloc_noprof include/linux/slab.h:1312 [inline]
 tomoyo_print_bprm security/tomoyo/audit.c:26 [inline]
 tomoyo_init_log+0xc4f/0x20c0 security/tomoyo/audit.c:262
 tomoyo_supervisor+0x506/0x1340 security/tomoyo/common.c:2232
 tomoyo_audit_env_log security/tomoyo/environ.c:37 [inline]
 tomoyo_env_perm+0x191/0x200 security/tomoyo/environ.c:64
 tomoyo_environ security/tomoyo/domain.c:673 [inline]
 tomoyo_find_next_domain+0x13d7/0x2010 security/tomoyo/domain.c:889
 tomoyo_bprm_check_security security/tomoyo/tomoyo.c:102 [inline]
 tomoyo_bprm_check_security+0x12d/0x1d0 security/tomoyo/tomoyo.c:92
 security_bprm_check+0x87/0x1e0 security/security.c:820
 search_binary_handler fs/exec.c:1769 [inline]
 exec_binprm fs/exec.c:1811 [inline]
 bprm_execve fs/exec.c:1867 [inline]
 bprm_execve+0x80b/0x1940 fs/exec.c:1843
 do_execveat_common.isra.0+0x4a5/0x580 fs/exec.c:1965
 __do_sys_execve fs/exec.c:2038 [inline]
 __se_sys_execve fs/exec.c:2032 [inline]
 __x64_sys_execve+0x93/0xd0 fs/exec.c:2032
page last free pid 5307 tgid 5307 ts 41998300083 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:4683 [inline]
 slab_alloc_node mm/slub.c:4996 [inline]
 kmem_cache_alloc_noprof+0x269/0x6a0 mm/slub.c:5010
 alloc_filename fs/namei.c:147 [inline]
 do_getname+0x35/0x390 fs/namei.c:187
 getname include/linux/fs.h:2557 [inline]
 getname_maybe_null include/linux/fs.h:2564 [inline]
 class_filename_maybe_null_constructor include/linux/fs.h:2588 [inline]
 vfs_fstatat+0xd0/0xe0 fs/stat.c:368
 __do_sys_newfstatat+0x9d/0x120 fs/stat.c:538
 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:
 ffff88801e389580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88801e389600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88801e389680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                    ^
 ffff88801e389700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88801e389780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/28 19:48 upstream 72d3fcf802c4 a3c7249d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root KASAN: slab-use-after-free Read in input_default_getkeycode
* Struck through repros no longer work on HEAD.