KASAN: use-after-free Read in lockref

KASAN: use-after-free Read in lockref_get
Status: upstream: reported on 2020/02/26 07:00
Reported-by: syzbot+603294af2d01acfdd6da@syzkaller.appspotmail.com
First crash: 94d, last: 28d

Sample crash report:

==================================================================
BUG: KASAN: use-after-free in __lock_acquire+0x3fa6/0x4c50 kernel/locking/lockdep.c:4225
Read of size 8 at addr ffff888089dd30a0 by task syz-executor.4/8575

CPU: 0 PID: 8575 Comm: syz-executor.4 Not tainted 5.7.0-rc2-syzkaller #0
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+0x188/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd3/0x315 mm/kasan/report.c:382
 __kasan_report.cold+0x35/0x4d mm/kasan/report.c:511
 kasan_report+0x33/0x50 mm/kasan/common.c:625
 __lock_acquire+0x3fa6/0x4c50 kernel/locking/lockdep.c:4225
 lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4934
 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
 _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
 lockref_get+0x11/0x50 include/linux/spinlock.h:353
 dget include/linux/dcache.h:321 [inline]
 simple_recursive_removal+0x43/0x730 fs/libfs.c:268
 debugfs_remove fs/debugfs/inode.c:703 [inline]
 debugfs_remove+0x59/0x80 fs/debugfs/inode.c:697
 blk_trace_free+0x31/0x130 kernel/trace/blktrace.c:311
 do_blk_trace_setup+0x711/0xb30 kernel/trace/blktrace.c:557
 __blk_trace_setup+0xca/0x180 kernel/trace/blktrace.c:571
 blk_trace_ioctl+0x162/0x2b0 kernel/trace/blktrace.c:712
 blkdev_ioctl+0xbe/0x660 block/ioctl.c:711
 block_ioctl+0xf9/0x140 fs/block_dev.c:2005
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl+0x11a/0x180 fs/ioctl.c:763
 __do_sys_ioctl fs/ioctl.c:772 [inline]
 __se_sys_ioctl fs/ioctl.c:770 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:770
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x45c829
Code: 0d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f447fecec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004e1540 RCX: 000000000045c829
RDX: 0000000020000080 RSI: 00000000c0481273 RDI: 0000000000000008
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000022a R14: 00000000004c4506 R15: 00007f447fecf6d4

Allocated by task 8575:
 save_stack+0x1b/0x40 mm/kasan/common.c:49
 set_track mm/kasan/common.c:57 [inline]
 __kasan_kmalloc mm/kasan/common.c:495 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:468
 slab_post_alloc_hook mm/slab.h:586 [inline]
 slab_alloc mm/slab.c:3320 [inline]
 kmem_cache_alloc+0x11b/0x740 mm/slab.c:3484
 __d_alloc+0x2b/0x8e0 fs/dcache.c:1690
 d_alloc+0x4a/0x240 fs/dcache.c:1769
 d_alloc_parallel+0xe8/0x1b10 fs/dcache.c:2521
 __lookup_slow+0x193/0x490 fs/namei.c:1515
 lookup_one_len+0x163/0x190 fs/namei.c:2548
 start_creating+0x12b/0x250 fs/debugfs/inode.c:338
 __debugfs_create_file+0x62/0x400 fs/debugfs/inode.c:383
 do_blk_trace_setup+0x351/0xb30 kernel/trace/blktrace.c:524
 __blk_trace_setup+0xca/0x180 kernel/trace/blktrace.c:571
 blk_trace_ioctl+0x162/0x2b0 kernel/trace/blktrace.c:712
 blkdev_ioctl+0xbe/0x660 block/ioctl.c:711
 block_ioctl+0xf9/0x140 fs/block_dev.c:2005
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl+0x11a/0x180 fs/ioctl.c:763
 __do_sys_ioctl fs/ioctl.c:772 [inline]
 __se_sys_ioctl fs/ioctl.c:770 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:770
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

Freed by task 126:
 save_stack+0x1b/0x40 mm/kasan/common.c:49
 set_track mm/kasan/common.c:57 [inline]
 kasan_set_free_info mm/kasan/common.c:317 [inline]
 __kasan_slab_free+0xf7/0x140 mm/kasan/common.c:456
 __cache_free mm/slab.c:3426 [inline]
 kmem_cache_free+0x7f/0x320 mm/slab.c:3694
 rcu_do_batch kernel/rcu/tree.c:2206 [inline]
 rcu_core+0x59f/0x1370 kernel/rcu/tree.c:2433
 __do_softirq+0x26c/0x9f7 kernel/softirq.c:292

The buggy address belongs to the object at ffff888089dd3000
 which belongs to the cache dentry of size 304
The buggy address is located 160 bytes inside of
 304-byte region [ffff888089dd3000, ffff888089dd3130)
The buggy address belongs to the page:
page:ffffea00022774c0 refcount:1 mapcount:0 mapping:0000000027272d18 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002277448 ffffea0002272b88 ffff88821bc50540
raw: 0000000000000000 ffff888089dd3000 000000010000000b 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888089dd2f80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff888089dd3000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888089dd3080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff888089dd3100: fb fb fb fb fb fb fc fc fc fc fc fc fc fc 00 00
 ffff888089dd3180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (6):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Maintainers
ci-upstream-kasan-gce	2020/04/26 18:46	upstream	b2768df2	0ce7569e	.config	log	report	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce	2020/03/25 13:42	upstream	76ccd234	41f049cc	.config	log	report	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-smack-root	2020/03/22 17:16	upstream	b74b991f	78267cec	.config	log	report	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-smack-root	2020/03/21 20:39	upstream	5ad0ec0b	4288d95e	.config	log	report	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce	2020/02/26 03:02	upstream	f8788d86	59b57593	.config	log	report	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-linux-next-kasan-gce-root	2020/05/02 15:09	linux-next	ac935d22	58da4c35	.config	log	report	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk