RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000007
R13: 00000000000000cd R14: 00000000004d1868 R15: 0000000000000009
proc_fill_super: allocate dentry failed
==================================================================
BUG: KASAN: use-after-free in fast_dput fs/dcache.c:727 [inline]
BUG: KASAN: use-after-free in dput+0x53e/0xdf0 fs/dcache.c:846
Read of size 4 at addr ffff88808a701450 by task syz-executor.2/8623

CPU: 1 PID: 8623 Comm: syz-executor.2 Not tainted 5.6.0-next-20200411-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
 fast_dput fs/dcache.c:727 [inline]
 dput+0x53e/0xdf0 fs/dcache.c:846
 proc_kill_sb+0x73/0xf0 fs/proc/root.c:195
 deactivate_locked_super+0x8c/0xf0 fs/super.c:335
 vfs_get_super+0x258/0x2d0 fs/super.c:1212
 vfs_get_tree+0x89/0x2f0 fs/super.c:1547
 vfs_fsconfig_locked+0x22c/0x3c0 fs/fsopen.c:232
 __do_sys_fsconfig fs/fsopen.c:439 [inline]
 __se_sys_fsconfig fs/fsopen.c:314 [inline]
 __x64_sys_fsconfig+0x621/0x860 fs/fsopen.c:314
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x45c889
Code: ad b6 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 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffa07a53c78 EFLAGS: 00000246 ORIG_RAX: 00000000000001af
RAX: ffffffffffffffda RBX: 00007ffa07a546d4 RCX: 000000000045c889
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000006
RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000007
R13: 00000000000000cd R14: 00000000004d1868 R15: 0000000000000009

Allocated by task 8148:
 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_name+0x80/0xb0 fs/dcache.c:1831
 proc_setup_self+0xe4/0x3c0 fs/proc/self.c:44
 proc_fill_super+0x3fb/0x660 fs/proc/root.c:133
 vfs_get_super+0x12e/0x2d0 fs/super.c:1191
 vfs_get_tree+0x89/0x2f0 fs/super.c:1547
 vfs_fsconfig_locked+0x22c/0x3c0 fs/fsopen.c:232
 __do_sys_fsconfig fs/fsopen.c:439 [inline]
 __se_sys_fsconfig fs/fsopen.c:314 [inline]
 __x64_sys_fsconfig+0x621/0x860 fs/fsopen.c:314
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

Freed by task 8150:
 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 ffff88808a701450
 which belongs to the cache dentry of size 304
The buggy address is located 0 bytes inside of
 304-byte region [ffff88808a701450, ffff88808a701580)
The buggy address belongs to the page:
page:ffffea000229c040 refcount:1 mapcount:0 mapping:0000000029f33c3a index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002290e48 ffffea0002251dc8 ffff88821bc50540
raw: 0000000000000000 ffff88808a701000 000000010000000b 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88808a701300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88808a701380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88808a701400: 00 00 fc fc fc fc fc fc fc fc fb fb fb fb fb fb
                                                 ^
 ffff88808a701480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88808a701500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================