generic_make_request: Trying to write to read-only block-device nullb0 (partno 0)
generic_make_request: Trying to write to read-only block-device nullb0 (partno 0)
generic_make_request: Trying to write to read-only block-device nullb0 (partno 0)
==================================================================
BUG: KASAN: use-after-free in call_usermodehelper_exec_work+0x204/0x240 kernel/umh.c:195
Write of size 4 at addr ffff88009f343770 by task kworker/u4:2/36

CPU: 1 PID: 36 Comm: kworker/u4:2 Not tainted 4.17.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound call_usermodehelper_exec_work
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x15a/0x20d lib/dump_stack.c:113
 print_address_description.cold.6+0x9/0x211 mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0x242/0x307 mm/kasan/report.c:412
 __asan_report_store4_noabort+0x17/0x20 mm/kasan/report.c:437
 call_usermodehelper_exec_work+0x204/0x240 kernel/umh.c:195
 process_one_work+0x780/0x1570 kernel/workqueue.c:2145
 worker_thread+0xd0/0xc00 kernel/workqueue.c:2279
 kthread+0x316/0x3d0 kernel/kthread.c:240
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:412

Allocated by task 3561:
 save_stack mm/kasan/kasan.c:448 [inline]
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc.part.1+0x62/0xf0 mm/kasan/kasan.c:553
 kasan_kmalloc+0xaf/0xc0 mm/kasan/kasan.c:538
 kmem_cache_alloc_trace+0x152/0x3f0 mm/slab.c:3620
 kmalloc include/linux/slab.h:512 [inline]
 kzalloc include/linux/slab.h:701 [inline]
 call_usermodehelper_setup+0x65/0x2c0 kernel/umh.c:382
 kobject_uevent_env+0x8c2/0xe40 lib/kobject_uevent.c:608
 kobject_synth_uevent+0x5d9/0x833 lib/kobject_uevent.c:208
 uevent_store+0x1c/0x40 drivers/base/core.c:993
 dev_attr_store+0x37/0x70 drivers/base/core.c:713
 sysfs_kf_write+0xfd/0x150 fs/sysfs/file.c:139
 kernfs_fop_write+0x255/0x410 fs/kernfs/file.c:316
 __vfs_write+0xe3/0x860 fs/read_write.c:485
 vfs_write+0x150/0x4f0 fs/read_write.c:549
 ksys_write+0xcd/0x1b0 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+0x6e/0xb0 fs/read_write.c:607
 do_syscall_64+0xd0/0x4d0 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 16989:
 save_stack mm/kasan/kasan.c:448 [inline]
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x13c/0x220 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3498 [inline]
 kfree+0xcf/0x280 mm/slab.c:3813
 call_usermodehelper_freeinfo kernel/umh.c:45 [inline]
 umh_complete+0x52/0x60 kernel/umh.c:59
 call_usermodehelper_exec_async+0x465/0x550 kernel/umh.c:116
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:412

The buggy address belongs to the object at ffff88009f343700
 which belongs to the cache kmalloc-192 of size 192
The buggy address is located 112 bytes inside of
 192-byte region [ffff88009f343700, ffff88009f3437c0)
The buggy address belongs to the page:
page:ffffea00027cd0c0 count:1 mapcount:0 mapping:ffff88009f343000 index:0x0
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffff88009f343000 0000000000000000 0000000100000010
raw: ffffea0002903aa0 ffffea0002767a60 ffff8800aa800040 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88009f343600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88009f343680: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
>ffff88009f343700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                             ^
 ffff88009f343780: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff88009f343800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================