==================================================================
BUG: KASAN: use-after-free in string+0x2c6/0x2d0 lib/vsprintf.c:604
Read of size 1 at addr ffff8801d70ae840 by task syz-executor7/28541

CPU: 0 PID: 28541 Comm: syz-executor7 Not tainted 4.19.0-rc1+ #215
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0x242/0x30d mm/kasan/report.c:412
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:430
 string+0x2c6/0x2d0 lib/vsprintf.c:604
 vsnprintf+0x48f/0x1b60 lib/vsprintf.c:2293
 add_uevent_var+0x140/0x2f0 lib/kobject_uevent.c:659
 input_dev_uevent+0x15d/0x860 drivers/input/input.c:1594
 dev_uevent+0x340/0x7e0 drivers/base/core.c:1008
 kobject_uevent_env+0x45b/0x1110 lib/kobject_uevent.c:547
 kobject_uevent+0x1f/0x30 lib/kobject_uevent.c:636
 kobject_cleanup lib/kobject.c:649 [inline]
 kobject_release lib/kobject.c:691 [inline]
 kref_put include/linux/kref.h:70 [inline]
 kobject_put+0x1fb/0x280 lib/kobject.c:708
 put_device+0x20/0x30 drivers/base/core.c:2024
 input_put_device include/linux/input.h:349 [inline]
 evdev_free+0x4f/0x70 drivers/input/evdev.c:369
 device_release+0x7e/0x210 drivers/base/core.c:891
 kobject_cleanup lib/kobject.c:662 [inline]
 kobject_release lib/kobject.c:691 [inline]
 kref_put include/linux/kref.h:70 [inline]
 kobject_put+0x194/0x280 lib/kobject.c:708
 cdev_default_release+0x3e/0x50 fs/char_dev.c:607
 kobject_cleanup lib/kobject.c:662 [inline]
 kobject_release lib/kobject.c:691 [inline]
 kref_put include/linux/kref.h:70 [inline]
 kobject_put+0x194/0x280 lib/kobject.c:708
 cdev_put.part.0+0x36/0x50 fs/char_dev.c:368
 cdev_put+0x1f/0x30 fs/char_dev.c:366
 __fput+0x8ae/0xa40 fs/file_table.c:281
 ____fput+0x15/0x20 fs/file_table.c:309
 task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:193 [inline]
 exit_to_usermode_loop+0x318/0x380 arch/x86/entry/common.c:166
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
 do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x410c41
Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 34 19 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007fffaa6e4060 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000006 RCX: 0000000000410c41
RDX: 0000000000000000 RSI: 0000000000732ec8 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000001
R10: 00007fffaa6e3f90 R11: 0000000000000293 R12: 0000000000000008
R13: 00000000000f816e R14: 000000000000066f R15: badc0ffeebadface

Allocated by task 28542:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
 __do_kmalloc mm/slab.c:3718 [inline]
 __kmalloc_track_caller+0x14a/0x720 mm/slab.c:3733
 kstrndup+0x5f/0xe0 mm/util.c:98
 uinput_setup_device_legacy drivers/input/misc/uinput.c:549 [inline]
 uinput_write+0x2fb/0x1120 drivers/input/misc/uinput.c:621
 __vfs_write+0x117/0x9d0 fs/read_write.c:485
 vfs_write+0x1fc/0x560 fs/read_write.c:549
 ksys_write+0x101/0x260 fs/read_write.c:598
 __do_sys_write fs/read_write.c:610 [inline]
 __se_sys_write fs/read_write.c:607 [inline]
 __x64_sys_write+0x73/0xb0 fs/read_write.c:607
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 28542:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3498 [inline]
 kfree+0xd9/0x210 mm/slab.c:3813
 uinput_destroy_device+0xf8/0x250 drivers/input/misc/uinput.c:310
 uinput_ioctl_handler.isra.10+0x1439/0x2540 drivers/input/misc/uinput.c:880
 uinput_ioctl+0x4c/0x60 drivers/input/misc/uinput.c:1047
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685
 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702
 __do_sys_ioctl fs/ioctl.c:709 [inline]
 __se_sys_ioctl fs/ioctl.c:707 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801d70ae840
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 0 bytes inside of
 32-byte region [ffff8801d70ae840, ffff8801d70ae860)
The buggy address belongs to the page:
page:ffffea00075c2b80 count:1 mapcount:0 mapping:ffff8801dac001c0 index:0xffff8801d70aefc1
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffffea00076163c8 ffffea00073ce0c8 ffff8801dac001c0
raw: ffff8801d70aefc1 ffff8801d70ae000 000000010000003f 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801d70ae700: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8801d70ae780: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
>ffff8801d70ae800: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
                                           ^
 ffff8801d70ae880: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8801d70ae900: fb fb fb fb fc fc fc fc 00 02 fc fc fc fc fc fc
==================================================================