WARNING in rds_cmsg_rdma_args

Hello,

syzkaller hit the following crash on ad036b63ee57df9ab802a4eb20cbbbec66aa4520
git://git.cmpxchg.org/linux-mmots.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.
C reproducer is attached
syzkaller reproducer is attached. See https://goo.gl/kgGztJ
for information about syzkaller reproducers


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Reported-by: syzbot+ef175b5825285531eabf@syzkaller.appspotmail.com
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audit: type=1400 audit(1514947982.760:7): avc:  denied  { map } for  pid=3468 comm="syzkaller284818" path="/root/syzkaller284818499" dev="sda1" ino=16481 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
WARNING: CPU: 1 PID: 3468 at net/rds/rdma.c:617 rds_cmsg_rdma_args+0xe96/0x1360 net/rds/rdma.c:617
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 3468 Comm: syzkaller284818 Not tainted 4.15.0-rc6-mm1+ #50
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+0x137/0x198 lib/dump_stack.c:53
 panic+0x1e4/0x41c kernel/panic.c:183
 __warn+0x1dc/0x200 kernel/panic.c:547
 report_bug+0x211/0x2d0 lib/bug.c:184
 fixup_bug.part.11+0x37/0x80 arch/x86/kernel/traps.c:178
 fixup_bug arch/x86/kernel/traps.c:247 [inline]
 do_error_trap+0x249/0x290 arch/x86/kernel/traps.c:296
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
 invalid_op+0x22/0x40 arch/x86/entry/entry_64.S:1079
RIP: 0010:rds_cmsg_rdma_args+0xe96/0x1360 net/rds/rdma.c:617
RSP: 0018:ffff8801d4677700 EFLAGS: 00010293
RAX: ffff8801c04c0640 RBX: ffff8801d85e58b8 RCX: ffffffff84862946
RDX: 0000000000000000 RSI: 00000000014080c0 RDI: ffff8801bf9ddef0
RBP: ffff8801d4677890 R08: 0000000000000000 R09: 0000000000000000
R10: ffff8801d4677618 R11: 0000000000000001 R12: 0000000000000000
R13: ffff8801d85e5880 R14: ffff8801bff0cdc0 R15: 1ffff1003a8ceef4
 rds_cmsg_send net/rds/send.c:943 [inline]
 rds_sendmsg+0x1264/0x1e80 net/rds/send.c:1127
 sock_sendmsg_nosec net/socket.c:628 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:638
 ___sys_sendmsg+0x2f4/0x8c0 net/socket.c:2018
 __sys_sendmmsg+0x159/0x3c0 net/socket.c:2108
 SYSC_sendmmsg net/socket.c:2139 [inline]
 SyS_sendmmsg+0x35/0x60 net/socket.c:2134
 entry_SYSCALL_64_fastpath+0x23/0x9a
RIP: 0033:0x43fe49
RSP: 002b:00007fffcc68d268 EFLAGS: 00000217 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fe49
RDX: 0000000000000001 RSI: 000000002099ffc4 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000217 R12: 00000000004017b0
R13: 0000000000401840 R14: 0000000000000000 R15: 0000000000000000
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


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