KASAN: use-after-free Read in input_dev_uevent (2)

Status: upstream: reported C repro on 2026/04/10 14:12
Bug presence: origin:lts
[Documentation on labels]
Reported-by: syzbot+5f8233c5d5e4b76dcf51@syzkaller.appspotmail.com
First crash: 105d, last: 105d
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2026/04/10 lts (merge base) f2ddafa93a25 C [report] KASAN: use-after-free Write in steam_input_open
2026/04/10 upstream (ToT) 9a9c8ce300cd C Didn't crash
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-6-1 KASAN: use-after-free Read in input_dev_uevent 19 1 502d 502d 0/2 auto-obsoleted due to no activity on 2025/06/08 06:58
android-54 KASAN: use-after-free Read in input_dev_uevent 19 1 504d 504d 0/2 auto-obsoleted due to no activity on 2025/06/05 14:59
upstream KASAN: slab-use-after-free Read in input_dev_uevent input 19 C done 7 1057d 1068d 23/29 fixed on 2023/10/12 12:48
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2026/04/25 13:42 14m retest repro android14-6.1 report log

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in string_nocheck lib/vsprintf.c:643 [inline]
BUG: KASAN: use-after-free in string+0x21f/0x2b0 lib/vsprintf.c:725
Read of size 1 at addr ffff888130f7d4c9 by task udevd/102

CPU: 1 PID: 102 Comm: udevd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
 <TASK>
 __dump_stack+0x21/0x24 lib/dump_stack.c:88
 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106
 print_address_description+0x71/0x200 mm/kasan/report.c:316
 print_report+0x4a/0x60 mm/kasan/report.c:420
 kasan_report+0x122/0x150 mm/kasan/report.c:524
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report_generic.c:348
 string_nocheck lib/vsprintf.c:643 [inline]
 string+0x21f/0x2b0 lib/vsprintf.c:725
 vsnprintf+0xec4/0x1990 lib/vsprintf.c:2805
 add_uevent_var+0x1d4/0x450 lib/kobject_uevent.c:680
 input_dev_uevent+0x1ce/0xa20 drivers/input/input.c:1765
 dev_uevent+0x49a/0x530 drivers/base/core.c:2623
 uevent_show+0x1cb/0x350 drivers/base/core.c:2672
 dev_attr_show+0x64/0xe0 drivers/base/core.c:2373
 sysfs_kf_seq_show+0x280/0x3a0 fs/sysfs/file.c:59
 kernfs_seq_show+0x12a/0x180 fs/kernfs/file.c:223
 seq_read_iter+0x4c4/0xdd0 fs/seq_file.c:230
 kernfs_fop_read_iter+0x14a/0x4e0 fs/kernfs/file.c:297
 call_read_iter include/linux/fs.h:2276 [inline]
 new_sync_read fs/read_write.c:389 [inline]
 vfs_read+0x454/0x910 fs/read_write.c:470
 ksys_read+0x149/0x250 fs/read_write.c:613
 __do_sys_read fs/read_write.c:623 [inline]
 __se_sys_read fs/read_write.c:621 [inline]
 __x64_sys_read+0x7b/0x90 fs/read_write.c:621
 x64_sys_call+0x2f/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f5343aa7407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffd9f2c8070 EFLAGS: 00000202 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007f534418c880 RCX: 00007f5343aa7407
RDX: 0000000000001000 RSI: 000055fabf7e2630 RDI: 000000000000000c
RBP: 00007f5343befff0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 000000000000000a
R13: 00007f5343befea0 R14: 0000000000000000 R15: 000055fabf768230
 </TASK>

Allocated by task 384:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_alloc_info+0x25/0x30 mm/kasan/generic.c:505
 ____kasan_kmalloc mm/kasan/common.c:380 [inline]
 __kasan_kmalloc+0x95/0xb0 mm/kasan/common.c:389
 kasan_kmalloc include/linux/kasan.h:212 [inline]
 __do_kmalloc_node mm/slab_common.c:938 [inline]
 __kmalloc_node_track_caller+0xb1/0x1e0 mm/slab_common.c:958
 alloc_dr drivers/base/devres.c:116 [inline]
 devm_kmalloc+0x55/0x160 drivers/base/devres.c:833
 devm_kzalloc include/linux/device.h:211 [inline]
 steam_probe+0x11b/0xb60 drivers/hid/hid-steam.c:741
 hid_device_probe+0x268/0x390 drivers/hid/hid-core.c:2640
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x2cb/0x960 drivers/base/dd.c:639
 __driver_probe_device+0x198/0x280 drivers/base/dd.c:808
 driver_probe_device+0x54/0x3e0 drivers/base/dd.c:838
 __device_attach_driver+0x2e9/0x4a0 drivers/base/dd.c:966
 bus_for_each_drv+0x192/0x220 drivers/base/bus.c:429
 __device_attach+0x2b0/0x420 drivers/base/dd.c:1038
 device_initial_probe+0x1a/0x20 drivers/base/dd.c:1087
 bus_probe_device+0xc0/0x1f0 drivers/base/bus.c:489
 device_add+0xb4d/0xef0 drivers/base/core.c:3698
 hid_add_device+0x38f/0x540 drivers/hid/hid-core.c:2792
 usbhid_probe+0xbb6/0xfa0 drivers/hid/usbhid/hid-core.c:1442
 usb_probe_interface+0x63f/0xb20 drivers/usb/core/driver.c:397
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x2cb/0x960 drivers/base/dd.c:639
 __driver_probe_device+0x198/0x280 drivers/base/dd.c:808
 driver_probe_device+0x54/0x3e0 drivers/base/dd.c:838
 __device_attach_driver+0x2e9/0x4a0 drivers/base/dd.c:966
 bus_for_each_drv+0x192/0x220 drivers/base/bus.c:429
 __device_attach+0x2b0/0x420 drivers/base/dd.c:1038
 device_initial_probe+0x1a/0x20 drivers/base/dd.c:1087
 bus_probe_device+0xc0/0x1f0 drivers/base/bus.c:489
 device_add+0xb4d/0xef0 drivers/base/core.c:3698
 usb_set_configuration+0x19c2/0x1f10 drivers/usb/core/message.c:2165
 usb_generic_driver_probe+0x91/0x150 drivers/usb/core/generic.c:238
 usb_probe_device+0x159/0x270 drivers/usb/core/driver.c:294
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x2cb/0x960 drivers/base/dd.c:639
 __driver_probe_device+0x198/0x280 drivers/base/dd.c:808
 driver_probe_device+0x54/0x3e0 drivers/base/dd.c:838
 __device_attach_driver+0x2e9/0x4a0 drivers/base/dd.c:966
 bus_for_each_drv+0x192/0x220 drivers/base/bus.c:429
 __device_attach+0x2b0/0x420 drivers/base/dd.c:1038
 device_initial_probe+0x1a/0x20 drivers/base/dd.c:1087
 bus_probe_device+0xc0/0x1f0 drivers/base/bus.c:489
 device_add+0xb4d/0xef0 drivers/base/core.c:3698
 usb_new_device+0xa81/0x1550 drivers/usb/core/hub.c:2684
 hub_port_connect drivers/usb/core/hub.c:5594 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5734 [inline]
 port_event drivers/usb/core/hub.c:5898 [inline]
 hub_event+0x2aca/0x46b0 drivers/usb/core/hub.c:5980
 process_one_work+0x71f/0xc40 kernel/workqueue.c:2302
 worker_thread+0xa29/0x11e0 kernel/workqueue.c:2449
 kthread+0x281/0x320 kernel/kthread.c:386
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Freed by task 384:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x31/0x50 mm/kasan/generic.c:516
 ____kasan_slab_free+0x132/0x180 mm/kasan/common.c:242
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:250
 kasan_slab_free include/linux/kasan.h:178 [inline]
 slab_free_hook mm/slub.c:1750 [inline]
 slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1776
 slab_free mm/slub.c:3712 [inline]
 __kmem_cache_free+0xb7/0x1b0 mm/slub.c:3728
 kfree+0x6f/0xf0 mm/slab_common.c:990
 release_nodes+0xf9/0x230 drivers/base/devres.c:503
 devres_release_all+0x150/0x1b0 drivers/base/devres.c:532
 device_unbind_cleanup drivers/base/dd.c:530 [inline]
 __device_release_driver drivers/base/dd.c:1288 [inline]
 device_release_driver_internal+0x581/0x820 drivers/base/dd.c:1309
 device_release_driver+0x19/0x20 drivers/base/dd.c:1332
 bus_remove_device+0x2ee/0x350 drivers/base/bus.c:531
 device_del+0x6bc/0xec0 drivers/base/core.c:3886
 hid_remove_device drivers/hid/hid-core.c:2840 [inline]
 hid_destroy_device+0x6a/0x110 drivers/hid/hid-core.c:2859
 usbhid_disconnect+0x9f/0xc0 drivers/hid/usbhid/hid-core.c:1469
 usb_unbind_interface+0x223/0x8d0 drivers/usb/core/driver.c:459
 device_remove drivers/base/dd.c:550 [inline]
 __device_release_driver drivers/base/dd.c:1283 [inline]
 device_release_driver_internal+0x508/0x820 drivers/base/dd.c:1309
 device_release_driver+0x19/0x20 drivers/base/dd.c:1332
 bus_remove_device+0x2ee/0x350 drivers/base/bus.c:531
 device_del+0x6bc/0xec0 drivers/base/core.c:3886
 usb_disable_device+0x3a8/0x750 drivers/usb/core/message.c:1414
 usb_disconnect+0x31e/0x860 drivers/usb/core/hub.c:2339
 hub_port_connect drivers/usb/core/hub.c:5433 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5734 [inline]
 port_event drivers/usb/core/hub.c:5898 [inline]
 hub_event+0x1c1b/0x46b0 drivers/usb/core/hub.c:5980
 process_one_work+0x71f/0xc40 kernel/workqueue.c:2302
 process_scheduled_works kernel/workqueue.c:2365 [inline]
 worker_thread+0xcce/0x11e0 kernel/workqueue.c:2451
 kthread+0x281/0x320 kernel/kthread.c:386
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

The buggy address belongs to the object at ffff888130f7d400
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 201 bytes inside of
 512-byte region [ffff888130f7d400, ffff888130f7d600)

The buggy address belongs to the physical page:
page:ffffea0004c3df00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x130f7c
head:ffffea0004c3df00 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head|zone=1)
raw: 4000000000010200 0000000000000000 dead000000000122 ffff888100042f00
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x152a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_HARDWALL), pid 24, tgid 24 (kworker/1:0), ts 36939721795, free_ts 33403258306
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2670
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2677
 get_page_from_freelist+0x2d12/0x2d80 mm/page_alloc.c:4583
 __alloc_pages+0x1fa/0x610 mm/page_alloc.c:5924
 alloc_slab_page+0x6e/0xf0 include/linux/gfp.h:-1
 allocate_slab mm/slub.c:1967 [inline]
 new_slab+0x98/0x3d0 mm/slub.c:2020
 ___slab_alloc+0x6bd/0xb20 mm/slub.c:3177
 __slab_alloc+0x5e/0xa0 mm/slub.c:3263
 slab_alloc_node mm/slub.c:3348 [inline]
 __kmem_cache_alloc_node+0x203/0x2c0 mm/slub.c:3423
 __do_kmalloc_node mm/slab_common.c:937 [inline]
 __kmalloc+0xa1/0x1e0 mm/slab_common.c:951
 kmalloc include/linux/slab.h:568 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 neigh_alloc net/core/neighbour.c:494 [inline]
 ___neigh_create+0x6f6/0x1e20 net/core/neighbour.c:648
 __neigh_create+0x31/0x40 net/core/neighbour.c:737
 ip6_finish_output2+0xa56/0x18a0 net/ipv6/ip6_output.c:129
 __ip6_finish_output net/ipv6/ip6_output.c:205 [inline]
 ip6_finish_output+0x5f9/0xbb0 net/ipv6/ip6_output.c:216
 NF_HOOK_COND include/linux/netfilter.h:294 [inline]
 ip6_output+0x1fa/0x410 net/ipv6/ip6_output.c:237
 dst_output include/net/dst.h:453 [inline]
 NF_HOOK include/linux/netfilter.h:305 [inline]
 ndisc_send_skb+0x7dc/0xcc0 net/ipv6/ndisc.c:513
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 free_pages_prepare mm/page_alloc.c:1578 [inline]
 free_pcp_prepare mm/page_alloc.c:1652 [inline]
 free_unref_page_prepare+0x742/0x750 mm/page_alloc.c:3618
 free_unref_page+0x95/0x540 mm/page_alloc.c:3716
 free_the_page mm/page_alloc.c:863 [inline]
 __free_pages+0x67/0x100 mm/page_alloc.c:6014
 __vunmap+0x9c0/0xb80 mm/vmalloc.c:2739
 __vfree mm/vmalloc.c:2788 [inline]
 vfree+0x61/0x90 mm/vmalloc.c:2819
 kcov_put kernel/kcov.c:437 [inline]
 kcov_close+0x2b/0x50 kernel/kcov.c:533
 __fput+0x1fc/0x8f0 fs/file_table.c:320
 ____fput+0x15/0x20 fs/file_table.c:348
 task_work_run+0x1e1/0x250 kernel/task_work.c:203
 exit_task_work include/linux/task_work.h:39 [inline]
 do_exit+0xa35/0x2660 kernel/exit.c:886
 do_group_exit+0x210/0x2d0 kernel/exit.c:1028
 get_signal+0x13b5/0x1520 kernel/signal.c:2891
 arch_do_signal_or_restart+0xd1/0x1140 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x7a/0xb0 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:303

Memory state around the buggy address:
 ffff888130f7d380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888130f7d400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888130f7d480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                              ^
 ffff888130f7d500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888130f7d580: 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
2026/04/10 14:11 android14-6.1 b1e92db6a41f 38c8e246 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in input_dev_uevent
* Struck through repros no longer work on HEAD.