Empty option to dns_resolver key
==================================================================
WARNING: memcpy-param-overlap in generic_perform_write+0x4c6/0x990 mm/filemap.c:3146
__msan_memcpy(ffff8801cd2205c4, ffff8801cd2205c3, 13)
CPU: 1 PID: 5858 Comm: syz-executor4 Not tainted 4.16.0+ #84
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x185/0x1d0 lib/dump_stack.c:53
 __msan_memcpy+0x90/0x1f0 mm/kmsan/kmsan_instr.c:433
 memcpy_from_page lib/iov_iter.c:459 [inline]
 iov_iter_copy_from_user_atomic+0xb04/0x17d0 lib/iov_iter.c:792
==================================================================
BUG: KMSAN: uninit-value in core_kernel_text kernel/extable.c:77 [inline]
BUG: KMSAN: uninit-value in kernel_text_address+0x248/0x3a0 kernel/extable.c:127
CPU: 1 PID: 5858 Comm: syz-executor4 Not tainted 4.16.0+ #84
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x14a/0x1d0 lib/dump_stack.c:53
 kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067
 __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:676
 core_kernel_text kernel/extable.c:77 [inline]
 kernel_text_address+0x248/0x3a0 kernel/extable.c:127
 __kernel_text_address+0x34/0xe0 kernel/extable.c:107
 show_trace_log_lvl+0x954/0x1030 arch/x86/kernel/dumpstack.c:175
 show_stack+0xfc/0x150 arch/x86/kernel/dumpstack.c:236
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x185/0x1d0 lib/dump_stack.c:53
 __msan_memcpy+0x90/0x1f0 mm/kmsan/kmsan_instr.c:433
 memcpy_from_page lib/iov_iter.c:459 [inline]
 iov_iter_copy_from_user_atomic+0xb04/0x17d0 lib/iov_iter.c:792
 generic_perform_write+0x4c6/0x990 mm/filemap.c:3146
 __generic_file_write_iter+0x43b/0x990 mm/filemap.c:3263
 generic_file_write_iter+0x814/0xbf0 mm/filemap.c:3291
 do_iter_readv_writev+0x7bb/0x970 include/linux/fs.h:1776
 do_iter_write+0x30d/0xd40 fs/read_write.c:932
 vfs_iter_write+0x118/0x180 fs/read_write.c:945
 iter_file_splice_write+0xbc3/0x1710 fs/splice.c:749
 do_splice_from fs/splice.c:851 [inline]
 direct_splice_actor+0x19b/0x200 fs/splice.c:1018
 splice_direct_to_actor+0x764/0x1040 fs/splice.c:973
 do_splice_direct+0x335/0x540 fs/splice.c:1061
 do_sendfile+0x1067/0x1e40 fs/read_write.c:1413
 SYSC_sendfile64+0x1b3/0x300 fs/read_write.c:1468
 SyS_sendfile64+0x64/0x90 fs/read_write.c:1460
 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x3d/0xa2
RIP: 0033:0x455329
RSP: 002b:00007f851d7b4c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f851d7b56d4 RCX: 0000000000455329
RDX: 0000000020001000 RSI: 0000000000000014 RDI: 0000000000000014
RBP: 000000000072bf58 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000fec R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000004c6 R14: 00000000006fa330 R15: 0000000000000001

Local variable description: ----filepages.i@balance_dirty_pages_ratelimited
Variable was created at:
 balance_dirty_pages_ratelimited+0xd3/0x4880 mm/page-writeback.c:1864
 generic_perform_write+0x836/0x990 mm/filemap.c:3174
==================================================================