BUG: unable to handle kernel paging request in snd_pcm_format_set_silence

[syzbot <syzbot+f973e52978d95f818f69@syzkaller.appspotmail.com>]

Hello,

syzbot hit the following crash on upstream commit
f2d285669aae656dfeafa0bf25e86bbbc5d22329 (Tue Apr 3 17:45:39 2018 +0000)
Merge tag 'pm-4.17-rc1' of  
git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
syzbot dashboard link:  
https://syzkaller.appspot.com/bug?extid=f973e52978d95f818f69

So far this crash happened 2 times on upstream.
syzkaller reproducer:  
https://syzkaller.appspot.com/x/repro.syz?id=5368241429938176
Raw console output:  
https://syzkaller.appspot.com/x/log.txt?id=6066534392791040
Kernel config: https://syzkaller.appspot.com/x/.config?id=686016073509112605
compiler: gcc (GCC) 7.1.1 20170620
user-space arch: i386

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Reported-by: syzbot+f973e52978d95f818f69@syzkaller.appspotmail.com
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IPVS: ftp: loaded support on port[0] = 21
IPVS: ftp: loaded support on port[0] = 21
IPVS: ftp: loaded support on port[0] = 21
IPVS: ftp: loaded support on port[0] = 21
IPVS: ftp: loaded support on port[0] = 21
BUG: unable to handle kernel paging request at ffffc90004cc7000
PGD 1dad42067 P4D 1dad42067 PUD 1dad43067 PMD 1c5cb3067 PTE 0
Oops: 0002 [#1] SMP KASAN
Dumping ftrace buffer:
    (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 5516 Comm: syz-executor3 Not tainted 4.16.0+ #288
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:memset_erms+0x9/0x10 arch/x86/lib/memset_64.S:65
RSP: 0018:ffff8801d7fc7368 EFLAGS: 00010246
RAX: fffff520009b9600 RBX: ffffc90004cc7000 RCX: 0000000000104500
RDX: 0000000000104500 RSI: 0000000000000000 RDI: ffffc90004cc7000
RBP: ffff8801d7fc7388 R08: 0000000000000000 R09: ffffc90004cc7000
R10: 00000000000208a0 R11: fffff520009b969f R12: 0000000000104500
R13: 0000000000000000 R14: ffffffff88c9185c R15: 0000000000000010
FS:  0000000000000000(0000) GS:ffff8801db000000(0063) knlGS:00000000f7f5fb40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: ffffc90004cc7000 CR3: 00000001d765c000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  memset include/linux/string.h:330 [inline]
  snd_pcm_format_set_silence+0x13f/0x4b0 sound/core/pcm_misc.c:431
  loopback_prepare+0x92b/0xbf0 sound/drivers/aloop.c:347
  snd_pcm_do_prepare+0x58/0x90 sound/core/pcm_native.c:1640
  snd_pcm_action_single+0x70/0x110 sound/core/pcm_native.c:1084
  snd_pcm_action_nonatomic+0x95/0xa0 sound/core/pcm_native.c:1151
  snd_pcm_prepare+0x115/0x1a0 sound/core/pcm_native.c:1687
  snd_pcm_kernel_ioctl+0x97/0x240 sound/core/pcm_native.c:2998
  snd_pcm_oss_prepare+0x49/0x150 sound/core/oss/pcm_oss.c:1104
  snd_pcm_oss_make_ready+0xf9/0x130 sound/core/oss/pcm_oss.c:1132
  snd_pcm_oss_set_trigger+0x384/0x930 sound/core/oss/pcm_oss.c:1959
  snd_pcm_oss_poll+0x7aa/0xd60 sound/core/oss/pcm_oss.c:2727
  do_pollfd fs/select.c:832 [inline]
  do_poll fs/select.c:883 [inline]
  do_sys_poll+0x719/0x1050 fs/select.c:977
  SYSC_poll fs/select.c:1035 [inline]
  SyS_poll+0x10d/0x450 fs/select.c:1023
  do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline]
  do_fast_syscall_32+0x3ec/0xf9f arch/x86/entry/common.c:392
  entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7f63c99
RSP: 002b:00000000f7f5f0ac EFLAGS: 00000282 ORIG_RAX: 00000000000000a8
RAX: ffffffffffffffda RBX: 0000000020000100 RCX: 0000000000000001
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Code: 48 c1 e9 03 40 0f b6 f6 48 b8 01 01 01 01 01 01 01 01 48 0f af c6 f3  
48 ab 89 d1 f3 aa 4c 89 c8 c3 90 49 89 f9 40 88 f0 48 89 d1 <f3> aa 4c 89  
c8 c3 90 49 89 fa 40 0f b6 ce 48 b8 01 01 01 01 01
RIP: memset_erms+0x9/0x10 arch/x86/lib/memset_64.S:65 RSP: ffff8801d7fc7368
CR2: ffffc90004cc7000
---[ end trace 95a476f9da224f32 ]---


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