upstream boot error: KASAN: use-after-free Write in call_usermodehelper_exec_work

Status: fixed on 2018/07/09 18:05
Subsystems: kernel
[Documentation on labels]
Fix commit: bf956be520fb umh: fix race condition
First crash: 2205d, last: 2204d

Sample crash report:
cpuidle: using governor menu
ACPI: bus type PCI registered
PCI: Using configuration type 1 for base access
kworker/u4:2 (232) used greatest stack depth: 21992 bytes left
BUG: KASAN: use-after-free in call_usermodehelper_exec_work+0x2d3/0x310 kernel/umh.c:195
Write of size 4 at addr ffff8801d8bdd770 by task kworker/u4:0/7

CPU: 1 PID: 7 Comm: kworker/u4:0 Not tainted 4.17.0+ #94
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+0x1b9/0x294 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+0x242/0x2fe mm/kasan/report.c:412
 __asan_report_store4_noabort+0x17/0x20 mm/kasan/report.c:437
 call_usermodehelper_exec_work+0x2d3/0x310 kernel/umh.c:195
 process_one_work+0xc64/0x1b70 kernel/workqueue.c:2153
 worker_thread+0x181/0x13a0 kernel/workqueue.c:2296
 kthread+0x345/0x410 kernel/kthread.c:240
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412

Allocated by task 1:
 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
 kmem_cache_alloc_trace+0x152/0x780 mm/slab.c:3620
 kmalloc include/linux/slab.h:513 [inline]
 kzalloc include/linux/slab.h:706 [inline]
 call_usermodehelper_setup+0xe8/0x400 kernel/umh.c:382
 kobject_uevent_env+0xb21/0x1110 lib/kobject_uevent.c:608
 kobject_uevent+0x1f/0x30 lib/kobject_uevent.c:636
 kernel_add_sysfs_param kernel/params.c:798 [inline]
 param_sysfs_builtin kernel/params.c:833 [inline]
 param_sysfs_init+0x3f9/0x486 kernel/params.c:954
 do_one_initcall+0x127/0x913 init/main.c:884
 do_initcall_level init/main.c:952 [inline]
 do_initcalls init/main.c:960 [inline]
 do_basic_setup init/main.c:978 [inline]
 kernel_init_freeable+0x49b/0x58e init/main.c:1135
 kernel_init+0x11/0x1b3 init/main.c:1061
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412

Freed by task 514:
 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+0xd9/0x260 mm/slab.c:3813
 call_usermodehelper_freeinfo kernel/umh.c:45 [inline]
 umh_complete+0x7b/0x90 kernel/umh.c:59
 call_usermodehelper_exec_async+0x6e8/0x9e0 kernel/umh.c:116
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412

The buggy address belongs to the object at ffff8801d8bdd700
 which belongs to the cache kmalloc-192 of size 192
The buggy address is located 112 bytes inside of
 192-byte region [ffff8801d8bdd700, ffff8801d8bdd7c0)
The buggy address belongs to the page:
page:ffffea000762f740 count:1 mapcount:0 mapping:ffff8801da800040 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffffea0007627108 ffffea000762fbc8 ffff8801da800040
raw: 0000000000000000 ffff8801d8bdd000 0000000100000010 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801d8bdd600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801d8bdd680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8801d8bdd700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801d8bdd780: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8801d8bdd800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2018/06/10 12:06 upstream 3ca24ce9ff76 866118af .config console log report ci-upstream-kasan-gce
2018/06/09 09:27 upstream 7d3bf613e99a 866118af .config console log report ci-upstream-kasan-gce-root
2018/06/08 20:06 upstream 410feb75de24 866118af .config console log report ci-upstream-kasan-gce-root
2018/06/08 19:48 upstream 410feb75de24 866118af .config console log report ci-upstream-kasan-gce
2018/06/09 22:22 upstream a16afaf7928b 866118af .config console log report ci-upstream-kasan-gce-386
* Struck through repros no longer work on HEAD.