KASAN: use-after-free Read in string

KASAN: use-after-free Read in string
Status: fixed on 2019/06/14 18:22
Reported-by: syzbot+f648cfb7e0b52bf7ae32@syzkaller.appspotmail.com
Fix commit: c03a0fd0 kobject: Don't trigger kobject_uevent(KOBJ_REMOVE) twice.
First crash: 1020d, last: 777d

duplicates (1):
Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
KASAN: use-after-free Read in add_uevent_var	C	done		3	774d	774d	0/22	closed as dup on 2019/05/05 08:45

similar bugs (2):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
linux-4.14	KASAN: use-after-free Read in string				1	782d	782d	0/1	auto-closed as invalid on 2019/10/23 10:48
linux-4.19	KASAN: use-after-free Read in string				2	781d	790d	0/1	auto-closed as invalid on 2019/10/24 04:08

Sample crash report:

RDX: 0000000000000001 RSI: 0000000000005502 RDI: 0000000000000004
RBP: 00000000006cf018 R08: 0000000000000001 R09: 0000000000000038
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000006
R13: ffffffffffffffff R14: 0000000000000000 R15: 0000000000000000
==================================================================
BUG: KASAN: use-after-free in string+0x2c6/0x2d0 lib/vsprintf.c:604
Read of size 1 at addr ffff8801d79c5080 by task syz-executor215/4685

CPU: 1 PID: 4685 Comm: syz-executor215 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
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x1ae4/0x26e0 kernel/exit.c:867
 do_group_exit+0x177/0x440 kernel/exit.c:970
 __do_sys_exit_group kernel/exit.c:981 [inline]
 __se_sys_exit_group kernel/exit.c:979 [inline]
 __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:979
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x443a68
Code: Bad RIP value.
RSP: 002b:00007fff70261298 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000443a68
RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
RBP: 00000000004c39c8 R08: 00000000000000e7 R09: ffffffffffffffd0
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00000000006d5180 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 4685:
 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 4685:
 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 ffff8801d79c5080
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 0 bytes inside of
 32-byte region [ffff8801d79c5080, ffff8801d79c50a0)
The buggy address belongs to the page:
page:ffffea00075e7140 count:1 mapcount:0 mapping:ffff8801dac001c0 index:0xffff8801d79c5fc1
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffffea00075e0908 ffffea00075e7408 ffff8801dac001c0
raw: ffff8801d79c5fc1 ffff8801d79c5000 000000010000003f 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801d79c4f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801d79c5000: 00 00 fc fc fc fc fc fc 00 00 00 fc fc fc fc fc
>ffff8801d79c5080: fb fb fb fb fc fc fc fc 07 fc fc fc fc fc fc fc
                   ^
 ffff8801d79c5100: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8801d79c5180: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
==================================================================

Crashes (247):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro
ci-upstream-kasan-gce-root	2018/08/30 22:34	upstream	58c3f14f	938220fd	.config	log	report	syz	C
ci-upstream-kasan-gce	2019/05/01 12:18	upstream	f2bc9c90	618456b4	.config	log	report
ci-upstream-kasan-gce-smack-root	2019/04/28 11:49	upstream	037904a2	b617407b	.config	log	report
ci-upstream-kasan-gce-root	2019/04/27 20:47	upstream	baf76f0c	b617407b	.config	log	report
ci-upstream-kasan-gce-smack-root	2019/04/27 03:18	upstream	d0473f97	b617407b	.config	log	report
ci-upstream-kasan-gce	2019/04/26 20:56	upstream	d0473f97	b617407b	.config	log	report
ci-upstream-kasan-gce-smack-root	2019/04/24 04:50	upstream	7142eaa5	4d3d6a50	.config	log	report
ci-upstream-kasan-gce	2019/04/22 16:50	upstream	085b7755	0a77c33c	.config	log	report
ci-upstream-kasan-gce	2019/04/22 11:54	upstream	085b7755	0a77c33c	.config	log	report
ci-upstream-kasan-gce-selinux-root	2019/04/22 01:10	upstream	085b7755	b0e8efcb	.config	log	report
ci-upstream-kasan-gce	2019/04/21 22:25	upstream	085b7755	b0e8efcb	.config	log	report
ci-upstream-kasan-gce-smack-root	2019/04/20 14:22	upstream	371dd432	b0e8efcb	.config	log	report
ci-upstream-kasan-gce	2019/04/20 02:46	upstream	3ecafda9	b0e8efcb	.config	log	report
ci-upstream-kasan-gce-root	2019/04/18 15:39	upstream	e53f31bf	b0e8efcb	.config	log	report
ci-upstream-kasan-gce-smack-root	2019/04/17 11:42	upstream	444fe991	b0e8efcb	.config	log	report
ci-upstream-kasan-gce	2019/04/16 07:15	upstream	5512320c	505ab413	.config	log	report
ci-upstream-kasan-gce-root	2019/04/15 19:42	upstream	dc4060a5	505ab413	.config	log	report
ci-upstream-kasan-gce-smack-root	2019/04/15 05:29	upstream	dc4060a5	505ab413	.config	log	report
ci-upstream-kasan-gce-smack-root	2019/04/14 17:08	upstream	4443f8e6	505ab413	.config	log	report
ci-upstream-kasan-gce-selinux-root	2019/04/14 10:36	upstream	4443f8e6	c402d8f1	.config	log	report
ci-upstream-kasan-gce-root	2019/04/12 19:10	upstream	8ee15f32	8916f5e1	.config	log	report
ci-upstream-kasan-gce-selinux-root	2019/04/10 13:44	upstream	0ee7fb36	65b612b7	.config	log	report
ci-upstream-kasan-gce	2019/04/08 02:19	upstream	3b046891	c34fde03	.config	log	report
ci-upstream-kasan-gce	2019/03/27 11:20	upstream	65ae6893	55684ce1	.config	log	report
ci-upstream-kasan-gce-smack-root	2019/03/25 15:41	upstream	8c2ffd91	2c86e0a5	.config	log	report
ci-upstream-kasan-gce	2019/03/24 17:55	upstream	1bdd3dbf	acbc5b7d	.config	log	report
ci-upstream-kasan-gce-smack-root	2019/03/24 04:38	upstream	a5ed1e96	a2cef203	.config	log	report
ci-upstream-kasan-gce-selinux-root	2019/03/23 17:13	upstream	a5ed1e96	a2cef203	.config	log	report
ci-upstream-kasan-gce	2019/03/21 21:36	upstream	54c49016	dce6e62f	.config	log	report
ci-upstream-kasan-gce	2019/03/19 04:36	upstream	9e98c678	46264c32	.config	log	report
ci-upstream-kasan-gce-smack-root	2019/03/15 17:28	upstream	f261c4e5	bab43553	.config	log	report
ci-upstream-kasan-gce-selinux-root	2019/03/15 14:35	upstream	f261c4e5	bab43553	.config	log	report
ci-upstream-kasan-gce	2019/03/14 11:27	upstream	fa3d493f	d09a902e	.config	log	report
ci-upstream-kasan-gce-selinux-root	2019/03/12 03:13	upstream	a089e4fe	12365b99	.config	log	report
ci-upstream-kasan-gce	2019/03/10 16:23	upstream	6cdc577a	12365b99	.config	log	report
ci-upstream-kasan-gce-selinux-root	2019/03/09 18:25	upstream	38e7571c	12365b99	.config	log	report
ci-upstream-kasan-gce-smack-root	2019/03/09 11:00	upstream	3601fe43	12365b99	.config	log	report
ci-upstream-kasan-gce	2019/03/08 16:24	upstream	610cd4ea	12365b99	.config	log	report
ci-upstream-kasan-gce	2019/03/08 13:18	upstream	610cd4ea	12365b99	.config	log	report
ci-upstream-kasan-gce-root	2018/08/30 20:47	upstream	58c3f14f	938220fd	.config	log	report
ci-upstream-kasan-gce-386	2019/04/30 13:31	upstream	83a50840	20f16bef	.config	log	report
ci-upstream-kasan-gce-386	2019/04/27 02:00	upstream	d0473f97	b617407b	.config	log	report
ci-upstream-kasan-gce-386	2019/03/16 19:30	upstream	9c7dc824	bab43553	.config	log	report
ci-upstream-kasan-gce-386	2019/03/15 18:39	upstream	f261c4e5	bab43553	.config	log	report
ci-upstream-kasan-gce-386	2019/03/10 20:44	upstream	065b6c4c	12365b99	.config	log	report
ci-upstream-kasan-gce-386	2019/03/10 14:30	upstream	6cdc577a	12365b99	.config	log	report
ci-upstream-kasan-gce-386	2019/03/08 03:35	upstream	1fc1cd83	4b69c3cb	.config	log	report
ci-upstream-kasan-gce-386	2019/03/05 11:12	upstream	cd2a3bf0	bb91cf81	.config	log	report
ci-upstream-linux-next-kasan-gce-root	2019/03/19 23:00	linux-next	75e6a83b	e4549234	.config	log	report
ci-upstream-linux-next-kasan-gce-root	2019/03/19 16:58	linux-next	75e6a83b	e4549234	.config	log	report
ci-upstream-linux-next-kasan-gce-root	2019/03/15 22:07	linux-next	cf08baa2	bab43553	.config	log	report
ci-upstream-linux-next-kasan-gce-root	2019/03/12 05:32	linux-next	cf08baa2	12365b99	.config	log	report
ci-upstream-linux-next-kasan-gce-root	2019/03/04 22:06	linux-next	5d57915a	7c693b52	.config	log	report