TCP: request_sock_TCP: Possible SYN flooding on port 20004. Sending cookies.  Check SNMP counters.
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 25535 Comm: syz-executor4 Not tainted 4.13.0-rc2+ #9
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d36365c0 task.stack: ffff8801c3950000
RIP: 0010:bdev_read_page+0x38/0x210 fs/block_dev.c:671
RSP: 0018:ffff8801c3956908 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc9000547d000
RDX: 000000000000001c RSI: ffffffff81b28680 RDI: 00000000000000e0
RBP: ffff8801c3956938 R08: ffff8801c3956e20 R09: ffff8801c3956d20
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000014300 R14: ffffea00063f1348 R15: 0000000000000000
FS:  00007f6a768b1700(0000) GS:ffff8801dc100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001ddbc24000 CR3: 00000001d5d79000 CR4: 00000000001426e0
Call Trace:
 do_mpage_readpage+0x1507/0x19e0 fs/mpage.c:281
 mpage_readpages+0x626/0x8a0 fs/mpage.c:382
 blkdev_readpages+0x2c/0x40 fs/block_dev.c:589
 read_pages mm/readahead.c:121 [inline]
 __do_page_cache_readahead+0x6c6/0xc00 mm/readahead.c:199
 ra_submit mm/internal.h:66 [inline]
 do_sync_mmap_readahead mm/filemap.c:2284 [inline]
 filemap_fault+0xb09/0x1a70 mm/filemap.c:2360
 __do_fault+0xe1/0x3c0 mm/memory.c:2973
 do_read_fault mm/memory.c:3375 [inline]
 do_fault mm/memory.c:3475 [inline]
 handle_pte_fault mm/memory.c:3705 [inline]
 __handle_mm_fault+0x1a38/0x3730 mm/memory.c:3823
 handle_mm_fault+0x144/0x490 mm/memory.c:3860
 faultin_page mm/gup.c:477 [inline]
 __get_user_pages+0x4f8/0x15d0 mm/gup.c:674
 populate_vma_page_range+0x20e/0x2f0 mm/gup.c:1127
 __mm_populate+0x23a/0x450 mm/gup.c:1177
 mm_populate include/linux/mm.h:2116 [inline]
 vm_mmap_pgoff+0x241/0x280 mm/util.c:338
 SYSC_mmap_pgoff mm/mmap.c:1517 [inline]
 SyS_mmap_pgoff+0x462/0x5f0 mm/mmap.c:1475
 SYSC_mmap arch/x86/kernel/sys_x86_64.c:98 [inline]
 SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:89
 entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x4512c9
RSP: 002b:00007f6a768b0c08 EFLAGS: 00000216 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 0000000000718000 RCX: 00000000004512c9
RDX: 0000000000000003 RSI: 0000000000004000 RDI: 00000000207c3000
RBP: 0000000000000086 R08: 0000000000000017 R09: 0000000000000000
R10: 0000000000002851 R11: 0000000000000216 R12: 00000000004b973d
R13: 00000000ffffffff R14: 0000000020940000 R15: 00000000000006e0
Code: 89 f5 53 48 89 fb 48 83 ec 08 48 89 55 d0 e8 e0 e8 ba ff 48 8d bb e0 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 78 01 00 00 4c 8b a3 e0 00 00 00 48 b8 00 00 
RIP: bdev_read_page+0x38/0x210 fs/block_dev.c:671 RSP: ffff8801c3956908
---[ end trace aadbe098b33fe351 ]---