BUG: unable to handle kernel NULL pointer dereference at 00000000000000fd
IP: qlist_free_all+0x37/0x160 mm/kasan/quarantine.c:163
PGD 1d1d57067 P4D 1d1d57067 PUD 1d1e94067 PMD 0 
Oops: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 23863 Comm: syz-executor6 Not tainted 4.16.0-rc7+ #371
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:qlist_free_all+0x37/0x160 mm/kasan/quarantine.c:163
RSP: 0018:ffff8801b97c7848 EFLAGS: 00010246
RAX: ffff8801d3c5cdc0 RBX: 0000000000000282 RCX: 0000000000000000
RDX: ffffea00074f1700 RSI: ffffea00072acd9f RDI: 0000000000000282
RBP: ffff8801b97c7880 R08: 1ffff100372f8ed7 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000001 R14: ffff8801d3c5cdc0 R15: ffffffff87acabe0
FS:  0000000000a98940(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000000000fd CR3: 00000001d200b005 CR4: 00000000001606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 quarantine_reduce+0x141/0x170 mm/kasan/quarantine.c:259
 kasan_kmalloc+0xca/0xe0 mm/kasan/kasan.c:537
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
 slab_post_alloc_hook mm/slab.h:443 [inline]
 slab_alloc mm/slab.c:3380 [inline]
 kmem_cache_alloc+0x11b/0x760 mm/slab.c:3540
 kmem_cache_zalloc include/linux/slab.h:691 [inline]
 mmap_region+0x7ee/0x15a0 mm/mmap.c:1673
 do_mmap+0x6c0/0xe00 mm/mmap.c:1483
 do_mmap_pgoff include/linux/mm.h:2223 [inline]
 vm_mmap_pgoff+0x1de/0x280 mm/util.c:355
 SYSC_mmap_pgoff mm/mmap.c:1533 [inline]
 SyS_mmap_pgoff+0x23b/0x5f0 mm/mmap.c:1491
 SYSC_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
 SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:91
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45490a
RSP: 002b:0000000000a3e7f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045490a
RDX: 0000000000000003 RSI: 0000000000021000 RDI: 0000000000000000
RBP: ffffffffffffffff R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000020022 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000021000 R14: 0000000000020022 R15: 0000000000000000
Code: 55 48 89 e5 41 57 41 56 41 55 41 54 49 c7 c7 e0 ab ac 87 53 49 89 f4 48 83 ec 10 48 89 7d c8 4d 85 e4 4d 89 e5 0f 84 c8 00 00 00 <49> 63 95 fc 00 00 00 4c 8b 30 48 29 d0 49 83 3f 00 48 89 c6 0f 
RIP: qlist_free_all+0x37/0x160 mm/kasan/quarantine.c:163 RSP: ffff8801b97c7848
CR2: 00000000000000fd
---[ end trace 6bf66f1d45470cd2 ]---