linux-kernel - BUG: unable to handle kernel paging request in dput

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Message-ID: <000000000000b6f0d9056de4dd54@google.com>
Date:   Tue, 05 Jun 2018 06:17:03 -0700
From:   syzbot <syzbot+4f39ae71208fef432d97@...kaller.appspotmail.com>
To:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        syzkaller-bugs@...glegroups.com, viro@...iv.linux.org.uk
Subject: BUG: unable to handle kernel paging request in dput

Hello,

syzbot found the following crash on:

HEAD commit:    716a685fdb89 Merge branch 'x86-hyperv-for-linus' of git://..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10224f2f800000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4f65cd4286737868
dashboard link: https://syzkaller.appspot.com/bug?extid=4f39ae71208fef432d97
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=10626def800000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=151d6af7800000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+4f39ae71208fef432d97@...kaller.appspotmail.com

RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000440449
RDX: 00000000000000a6 RSI: 0000000020000100 RDI: 0000000000000003
RBP: 00000000006cb018 R08: 0000000000000001 R09: 65732f636f720031
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000004
R13: ffffffffffffffff R14: 0000000000000000 R15: 0000000000000000
BUG: unable to handle kernel paging request at fffffffffffffff4
PGD 8c6d067 P4D 8c6d067 PUD 8c6f067 PMD 0
Oops: 0000 [#1] SMP KASAN
CPU: 0 PID: 4491 Comm: syz-executor505 Not tainted 4.17.0+ #84
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:fast_dput fs/dcache.c:716 [inline]
RIP: 0010:dput.part.26+0x117/0x780 fs/dcache.c:835
Code: ff 09 b3 ff 45 84 ff 0f 84 e2 03 00 00 e8 21 09 b3 ff 48 89 d8 48 c1  
e8 03 42 0f b6 04 28 84 c0 74 08 3c 03 0f 8e 04 05 00 00 <44> 8b 3b 48 8d  
83 80 00 00 00 31 ff 48 89 85 70 ff ff ff 41 83 e7
RSP: 0018:ffff8801b6f979f8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: fffffffffffffff4 RCX: ffffffff81c64bd2
RDX: 0000000000000000 RSI: ffffffff81c647df RDI: 0000000000000001
RBP: ffff8801b6f97a90 R08: ffff8801b04205c0 R09: ffffed003b5c46d6
R10: ffffed003b5c46d6 R11: ffff8801dae236b3 R12: 1ffff10036df2f41
R13: dffffc0000000000 R14: ffffed0036df2f45 R15: 0000000000000001
FS:  0000000001150880(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffff4 CR3: 00000001d06ad000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  dput+0x15/0x20 fs/dcache.c:830
  proc_fill_cache+0x230/0x660 fs/proc/base.c:1910
  proc_ns_dir_readdir+0x3f5/0x560 fs/proc/namespaces.c:126
  iterate_dir+0x4b0/0x5d0 fs/readdir.c:51
  ksys_getdents64+0x21c/0x430 fs/readdir.c:314
  __do_sys_getdents64 fs/readdir.c:333 [inline]
  __se_sys_getdents64 fs/readdir.c:330 [inline]
  __x64_sys_getdents64+0x73/0xb0 fs/readdir.c:330
  do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x440449
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 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 5b 14 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fff292cc9d8 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000440449
RDX: 00000000000000a6 RSI: 0000000020000100 RDI: 0000000000000003
RBP: 00000000006cb018 R08: 0000000000000001 R09: 65732f636f720031
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000004
R13: ffffffffffffffff R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
Dumping ftrace buffer:
    (ftrace buffer empty)
CR2: fffffffffffffff4
---[ end trace 81153e86b0cb1bde ]---
RIP: 0010:fast_dput fs/dcache.c:716 [inline]
RIP: 0010:dput.part.26+0x117/0x780 fs/dcache.c:835
Code: ff 09 b3 ff 45 84 ff 0f 84 e2 03 00 00 e8 21 09 b3 ff 48 89 d8 48 c1  
e8 03 42 0f b6 04 28 84 c0 74 08 3c 03 0f 8e 04 05 00 00 <44> 8b 3b 48 8d  
83 80 00 00 00 31 ff 48 89 85 70 ff ff ff 41 83 e7
RSP: 0018:ffff8801b6f979f8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: fffffffffffffff4 RCX: ffffffff81c64bd2
RDX: 0000000000000000 RSI: ffffffff81c647df RDI: 0000000000000001
RBP: ffff8801b6f97a90 R08: ffff8801b04205c0 R09: ffffed003b5c46d6
R10: ffffed003b5c46d6 R11: ffff8801dae236b3 R12: 1ffff10036df2f41
R13: dffffc0000000000 R14: ffffed0036df2f45 R15: 0000000000000001
FS:  0000000001150880(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffff4 CR3: 00000001d06ad000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
This bug is generated by a bot. It may contain errors.
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