KASAN: out-of-bounds Read in __list_del_entry_valid

[syzbot]

Hello,

syzkaller hit the following crash on
9829d9f31f6c0e4984545e03032f14ccca6eeb68
git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.

syzkaller reproducer is attached. See https://goo.gl/kgGztJ
for information about syzkaller reproducers
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org
vi...@zeniv.linux.org.uk]

BUG: KASAN: out-of-bounds in __list_del_entry_valid+0x10b/0x150
lib/list_debug.c:51
Read of size 8 at addr ffff8800391efa80 by task syz-executor3/5431

CPU: 3 PID: 5431 Comm: syz-executor3 Not tainted 4.13.0-next-20170904+ #14
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:16 [inline]
dump_stack+0x194/0x257 lib/dump_stack.c:52
print_address_description+0x73/0x250 mm/kasan/report.c:252
kasan_report_error mm/kasan/report.c:351 [inline]
kasan_report+0x24e/0x340 mm/kasan/report.c:409
__asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
__list_del_entry_valid+0x10b/0x150 lib/list_debug.c:51
__list_del_entry include/linux/list.h:116 [inline]
list_del include/linux/list.h:124 [inline]
__remove_wait_queue include/linux/wait.h:182 [inline]
userfaultfd_event_wait_completion+0x519/0x910 fs/userfaultfd.c:591
dup_fctx fs/userfaultfd.c:687 [inline]
dup_userfaultfd_complete+0x2de/0x480 fs/userfaultfd.c:695
dup_mmap kernel/fork.c:726 [inline]
dup_mm kernel/fork.c:1179 [inline]
copy_mm+0xe9b/0x1310 kernel/fork.c:1233
copy_process.part.36+0x1eae/0x4af0 kernel/fork.c:1735
copy_process kernel/fork.c:1548 [inline]
_do_fork+0x1ef/0xfe0 kernel/fork.c:2027
SYSC_clone kernel/fork.c:2137 [inline]
SyS_clone+0x37/0x50 kernel/fork.c:2131
do_syscall_64+0x26c/0x8c0 arch/x86/entry/common.c:287
entry_SYSCALL64_slow_path+0x25/0x25
RIP: 0033:0x447299
RSP: 002b:00007f78ab587c08 EFLAGS: 00000282 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000447299
RDX: 0000000020d6f000 RSI: 0000000020d42fff RDI: 0000000000000000
RBP: 0000000000708160 R08: 0000000020497000 R09: 0000000000000000
R10: 0000000020a6bffc R11: 0000000000000282 R12: 00000000ffffffff
R13: 0000000000000450 R14: 00000000006e3510 R15: 0000000020d42fff

The buggy address belongs to the page:
page:ffffea0000e47bc0 count:0 mapcount:0 mapping: (null) index:0x0
flags: 0x100000000000000()
raw: 0100000000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: 0000000000000000 0000000100000001 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8800391ef980: 00 00 00 f1 f1 f1 f1 00 f2 f2 f2 f2 f2 f2 f2 00
ffff8800391efa00: f2 f2 f2 f2 f2 f2 f2 00 f2 f2 f2 f3 f3 f3 f3 00
> ffff8800391efa80: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
^
ffff8800391efb00: 00 f2 f2 f2 f2 f2 f2 f2 f8 f2 f2 f2 f2 f2 f2 f2
ffff8800391efb80: 00 f2 f2 f2 f3 f3 f3 f3 00 00 00 00 00 00 00 00
==================================================================


---
This bug is generated by a dumb bot. It may contain errors.
See https://goo.gl/tpsmEJ for details.
Direct all questions to syzk...@googlegroups.com.
Please credit me with: Reported-by: syzbot <syzk...@googlegroups.com>

syzbot will keep track of this bug report.
Once a fix for this bug is committed, please reply to this email with:
#syz fix: exact-commit-title
To mark this as a duplicate of another syzbot report, please reply with:
#syz dup: exact-subject-of-another-report
If it's a one-off invalid bug report, please reply with:
#syz invalid
Note: if the crash happens again, it will cause creation of a new bug
report.
Note: all commands must start from beginning of the line.
To upstream this report, please reply with:
#syz upstream

[Dmitry Vyukov]

Happened once 2 moths ago, I can't reproduce it now

#syz invalid

On Tue, Oct 31, 2017 at 2:57 PM, syzbot
<bot+1518b91279d5c477ed...@syzkaller.appspotmail.com>
wrote:

> --
> You received this message because you are subscribed to the Google Groups
> "syzkaller-upstream-moderation" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to syzkaller-upstream-m...@googlegroups.com.
> To post to this group, send email to
> syzkaller-upst...@googlegroups.com.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/syzkaller-upstream-moderation/001a1135a7f2d2bc8b055cd67620%40google.com.
> For more options, visit https://groups.google.com/d/optout.