KASAN: use-after-free Read in debugfs

KASAN: use-after-free Read in debugfs_remove
Status: upstream: reported C repro on 2019/06/23 14:51
Reported-by: syzbot+5d709bb1673168a5ada8@syzkaller.appspotmail.com
First crash: 215d, last: 6d21h

similar bugs (4):
Kernel	Title	Repro	Bisected	Count	Last	Reported	Patched	Status
upstream	KASAN: use-after-free Read in debugfs_remove (2)			1	644d	641d	6/16	fixed on 2018/05/17 10:02
upstream	KASAN: use-after-free Read in debugfs_remove (3)	C	cause+fix	88	5d14h	472d	0/16	upstream: reported C repro on 2018/10/10 08:09
upstream	KASAN: use-after-free Read in debugfs_remove			1	665d	664d	0/16	closed as invalid on 2018/04/10 15:18
linux-4.14	KASAN: use-after-free Read in debugfs_remove	C		9	26d	283d	0/1	upstream: reported C repro on 2019/04/17 06:08

Sample crash report:

devpts: called with bogus options
devpts: called with bogus options
devpts: called with bogus options
devpts: called with bogus options
==================================================================
BUG: KASAN: use-after-free in debugfs_remove+0x10d/0x130 fs/debugfs/inode.c:687
Read of size 8 at addr ffff88808d915300 by task kworker/1:2/3204

CPU: 1 PID: 3204 Comm: kworker/1:2 Not tainted 4.19.81 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events __blk_release_queue
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report mm/kasan/report.c:412 [inline]
 kasan_report.cold+0x8c/0x2ba mm/kasan/report.c:396
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 debugfs_remove+0x10d/0x130 fs/debugfs/inode.c:687
 blk_trace_free+0x38/0x140 kernel/trace/blktrace.c:312
 blk_trace_cleanup kernel/trace/blktrace.c:339 [inline]
 __blk_trace_remove+0x78/0xa0 kernel/trace/blktrace.c:352
 blk_trace_shutdown+0x67/0x90 kernel/trace/blktrace.c:752
 __blk_release_queue+0x260/0x540 block/blk-sysfs.c:855
 process_one_work+0x989/0x1750 kernel/workqueue.c:2153
kobject: 'iosched' (00000000ae720b42): kobject_uevent_env
 worker_thread+0x98/0xe40 kernel/workqueue.c:2296
 kthread+0x354/0x420 kernel/kthread.c:246
kobject: 'iosched' (00000000ae720b42): kobject_uevent_env: filter function caused the event to drop!
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

Allocated by task 7599:
 save_stack+0x45/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc mm/kasan/kasan.c:553 [inline]
 kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:531
 kasan_slab_alloc+0xf/0x20 mm/kasan/kasan.c:490
kobject: 'integrity' (00000000b9618528): kobject_add_internal: parent: 'loop0', set: '<NULL>'
 kmem_cache_alloc+0x12e/0x700 mm/slab.c:3559
 __d_alloc+0x2e/0x9c0 fs/dcache.c:1610
 d_alloc+0x4d/0x280 fs/dcache.c:1694
 d_alloc_parallel+0xf4/0x1bb0 fs/dcache.c:2441
 __lookup_slow+0x1ab/0x500 fs/namei.c:1654
 lookup_one_len+0x16d/0x1a0 fs/namei.c:2543
 start_creating fs/debugfs/inode.c:313 [inline]
 start_creating+0xbf/0x1e0 fs/debugfs/inode.c:289
 __debugfs_create_file+0x65/0x400 fs/debugfs/inode.c:352
 debugfs_create_file+0x5a/0x70 fs/debugfs/inode.c:404
 do_blk_trace_setup+0x376/0xb90 kernel/trace/blktrace.c:528
 __blk_trace_setup+0xe3/0x190 kernel/trace/blktrace.c:577
 blk_trace_ioctl+0x170/0x300 kernel/trace/blktrace.c:716
 blkdev_ioctl+0x126/0x1ab6 block/ioctl.c:587
 block_ioctl+0xee/0x130 fs/block_dev.c:1891
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0xd5f/0x1380 fs/ioctl.c:688
kobject: 'integrity' (00000000b9618528): kobject_uevent_env
 ksys_ioctl+0xab/0xd0 fs/ioctl.c:705
 __do_sys_ioctl fs/ioctl.c:712 [inline]
 __se_sys_ioctl fs/ioctl.c:710 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:710
 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
kobject: 'integrity' (00000000b9618528): kobject_uevent_env: filter function caused the event to drop!

Freed by task 7617:
 save_stack+0x45/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3503 [inline]
 kmem_cache_free+0x86/0x260 mm/slab.c:3765
 __d_free+0x20/0x30 fs/dcache.c:257
kobject: 'integrity' (00000000b9618528): kobject_uevent_env
 __rcu_reclaim kernel/rcu/rcu.h:236 [inline]
 rcu_do_batch kernel/rcu/tree.c:2584 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2897 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2864 [inline]
 rcu_process_callbacks+0xba0/0x1a30 kernel/rcu/tree.c:2881
 __do_softirq+0x25c/0x921 kernel/softirq.c:292

The buggy address belongs to the object at ffff88808d9152c0
 which belongs to the cache dentry(71:syz5) of size 288
The buggy address is located 64 bytes inside of
 288-byte region [ffff88808d9152c0, ffff88808d9153e0)
The buggy address belongs to the page:
page:ffffea0002364540 count:1 mapcount:0 mapping:ffff8880a14271c0 index:0x0
kobject: 'integrity' (00000000b9618528): kobject_uevent_env: filter function caused the event to drop!
flags: 0x1fffc0000000100(slab)
raw: 01fffc0000000100 ffffea00025e84c8 ffffea00025e9148 ffff8880a14271c0
raw: 0000000000000000 ffff88808d915000 000000010000000b ffff8880961c2e00
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff8880961c2e00

Memory state around the buggy address:
 ffff88808d915200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
kobject: 'integrity' (00000000b9618528): kobject_cleanup, parent           (null)
 ffff88808d915280: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff88808d915300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88808d915380: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff88808d915400: fc fc fc fc fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Fix bisection attempts:
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro
ci2-linux-4-19	2020/01/13 11:57	linux-4.19.y	dcd88898	af5c522d	.config	log	report	syz	C
ci2-linux-4-19	2019/12/14 10:39	linux-4.19.y	312017a4	af5c522d	.config	log	report	syz	C

Crashes (9):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	Maintainers
ci2-linux-4-19	2019/11/05 20:37	linux-4.19.y	ef244c30	af5c522d	.config	log	report	syz	C	gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, rafael@kernel.org
ci2-linux-4-19	2019/07/22 04:47	linux-4.19.y	be9b6782	1656845f	.config	log	report	syz	C
ci2-linux-4-19	2019/06/23 17:43	linux-4.19.y	78778071	3efccdd2	.config	log	report	syz	C	gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, rafael@kernel.org
ci2-linux-4-19	2020/01/18 13:29	linux-4.19.y	dc4ba5be	3de7aabb	.config	log	report			gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, rafael@kernel.org
ci2-linux-4-19	2020/01/14 11:14	linux-4.19.y	dcd88898	32881205	.config	log	report			gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, rafael@kernel.org
ci2-linux-4-19	2019/09/16 11:11	linux-4.19.y	db2d0b7c	55c50e70	.config	log	report			gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, rafael@kernel.org
ci2-linux-4-19	2019/08/16 09:22	linux-4.19.y	a5aa8058	8fd428a1	.config	log	report			gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, rafael@kernel.org
ci2-linux-4-19	2019/07/26 01:41	linux-4.19.y	be9b6782	732bc5a0	.config	log	report			gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, rafael@kernel.org
ci2-linux-4-19	2019/06/23 13:50	linux-4.19.y	78778071	3efccdd2	.config	log	report			gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, rafael@kernel.org