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From: syzbot <syzbot+ec3986119086fe4eec97@syzkaller.appspotmail.com>
To: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	miklos@szeredi.hu, syzkaller-bugs@googlegroups.com
Subject: KASAN: use-after-free Read in fuse_kill_sb_blk
Date: Mon, 30 Apr 2018 06:34:02 -0700	[thread overview]
Message-ID: <0000000000002aeada056b10e833@google.com> (raw)

Hello,

syzbot hit the following crash on upstream commit
6da6c0db5316275015e8cc2959f12a17584aeb64 (Sun Apr 29 21:17:42 2018 +0000)
Linux v4.17-rc3
syzbot dashboard link:  
https://syzkaller.appspot.com/bug?extid=ec3986119086fe4eec97

Unfortunately, I don't have any reproducer for this crash yet.
Raw console output:  
https://syzkaller.appspot.com/x/log.txt?id=6601664433750016
Kernel config:  
https://syzkaller.appspot.com/x/.config?id=6493557782959164711
compiler: gcc (GCC) 8.0.1 20180413 (experimental)

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+ec3986119086fe4eec97@syzkaller.appspotmail.com
It will help syzbot understand when the bug is fixed. See footer for  
details.
If you forward the report, please keep this part and the footer.

RDX: 00000000004ba2e5 RSI: 0000000020000080 RDI: 00000000200000c0
RBP: 00000000200000c0 R08: 00007fe260309b20 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
==================================================================
BUG: KASAN: use-after-free in __lock_acquire+0x3888/0x5140  
kernel/locking/lockdep.c:3310
Read of size 8 at addr ffff8801cc7b1dc8 by task syz-executor0/25572

CPU: 0 PID: 25572 Comm: syz-executor0 Not tainted 4.17.0-rc3+ #25
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+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_load8_noabort+0x14/0x20 mm/kasan/report.c:433
  __lock_acquire+0x3888/0x5140 kernel/locking/lockdep.c:3310
  lock_acquire+0x1dc/0x520 kernel/locking/lockdep.c:3920
  down_write+0x87/0x120 kernel/locking/rwsem.c:70
  fuse_kill_sb_blk+0x50/0xb0 fs/fuse/inode.c:1230
  deactivate_locked_super+0x97/0x100 fs/super.c:316
  mount_bdev+0x37d/0x3e0 fs/super.c:1166
  fuse_mount_blk+0x34/0x40 fs/fuse/inode.c:1222
  mount_fs+0xae/0x328 fs/super.c:1267
  vfs_kern_mount.part.34+0xd4/0x4d0 fs/namespace.c:1037
  vfs_kern_mount fs/namespace.c:1027 [inline]
  do_new_mount fs/namespace.c:2518 [inline]
  do_mount+0x564/0x3070 fs/namespace.c:2848
  ksys_mount+0x12d/0x140 fs/namespace.c:3064
  __do_sys_mount fs/namespace.c:3078 [inline]
  __se_sys_mount fs/namespace.c:3075 [inline]
  __x64_sys_mount+0xbe/0x150 fs/namespace.c:3075
  do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x455979
RSP: 002b:00007fe260309b08 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000000000014 RCX: 0000000000455979
RDX: 00000000004ba2e5 RSI: 0000000020000080 RDI: 00000000200000c0
RBP: 00000000200000c0 R08: 00007fe260309b20 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 25572:
  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:512 [inline]
  fuse_fill_super+0xc92/0x1e20 fs/fuse/inode.c:1096
  mount_bdev+0x30c/0x3e0 fs/super.c:1164
  fuse_mount_blk+0x34/0x40 fs/fuse/inode.c:1222
  mount_fs+0xae/0x328 fs/super.c:1267
  vfs_kern_mount.part.34+0xd4/0x4d0 fs/namespace.c:1037
  vfs_kern_mount fs/namespace.c:1027 [inline]
  do_new_mount fs/namespace.c:2518 [inline]
  do_mount+0x564/0x3070 fs/namespace.c:2848
  ksys_mount+0x12d/0x140 fs/namespace.c:3064
  __do_sys_mount fs/namespace.c:3078 [inline]
  __se_sys_mount fs/namespace.c:3075 [inline]
  __x64_sys_mount+0xbe/0x150 fs/namespace.c:3075
  do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 25568:
  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
  __rcu_reclaim kernel/rcu/rcu.h:173 [inline]
  rcu_do_batch kernel/rcu/tree.c:2675 [inline]
  invoke_rcu_callbacks kernel/rcu/tree.c:2930 [inline]
  __rcu_process_callbacks kernel/rcu/tree.c:2897 [inline]
  rcu_process_callbacks+0xa69/0x15f0 kernel/rcu/tree.c:2914
  __do_softirq+0x2e0/0xaf5 kernel/softirq.c:285

The buggy address belongs to the object at ffff8801cc7b1b00
  which belongs to the cache kmalloc-1024 of size 1024
The buggy address is located 712 bytes inside of
  1024-byte region [ffff8801cc7b1b00, ffff8801cc7b1f00)
The buggy address belongs to the page:
page:ffffea000731ec00 count:1 mapcount:0 mapping:ffff8801cc7b0000  
index:0xffff8801cc7b1680 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff8801cc7b0000 ffff8801cc7b1680 0000000100000006
raw: ffffea0006fdc420 ffffea0006d5b1a0 ffff8801da800ac0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff8801cc7b1c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff8801cc7b1d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8801cc7b1d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                               ^
  ffff8801cc7b1e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff8801cc7b1e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
This bug is generated by a dumb bot. It may contain errors.
See https://goo.gl/tpsmEJ for details.
Direct all questions to syzkaller@googlegroups.com.

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             reply	other threads:[~2018-04-30 13:34 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-30 13:34 syzbot [this message]
2018-05-01 10:03 ` Tetsuo Handa
2018-05-09 11:01   ` [PATCH] fuse: don't keep dead fuse_conn at fuse_fill_super() Tetsuo Handa
2018-05-19 14:03     ` Tetsuo Handa
2018-05-31 10:19     ` Miklos Szeredi

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