BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
IP: [<ffffffff818a6c49>] memcmp+0x9/0x40 lib/string.c:771
kobject: 'loop0' (ffff88003d4bd0a0): kobject_uevent_env
kobject: 'loop0' (ffff88003d4bd0a0): fill_kobj_path: path = '/devices/virtual/block/loop0'
PGD 7788a067 PUD 7daa2067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP 
Modules linked in:
CPU: 0 PID: 17899 Comm: syz-executor4 Not tainted 4.5.0-rc6+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
task: ffff880039f84080 ti: ffff880038d98000 task.ti: ffff880038d98000
RIP: 0010:[<ffffffff818a6c49>]  [<ffffffff818a6c49>] memcmp+0x9/0x40 lib/string.c:771
RSP: 0018:ffff880038d9bde0  EFLAGS: 00010202
kobject: 'loop2' (ffff88003d4998a0): kobject_uevent_env
kobject: 'loop2' (ffff88003d4998a0): fill_kobj_path: path = '/devices/virtual/block/loop2'
RAX: ffffffff844b4cc0 RBX: 0000000000000000 RCX: 000000000000004e
RDX: 0000000000000008 RSI: ffff880038d9be40 RDI: 0000000000000008
RBP: ffff880038d9bde0 R08: ffff880039f84890 R09: 0000000000000000
R10: ffffffff83272ac0 R11: 0000000000ad0024 R12: 0000000000000000
R13: 0000000000000000 R14: ffff88003b5dc000 R15: 0000000000004e21
FS:  00007f8c275ed700(0000) GS:ffff88003ec00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000008 CR3: 0000000078104000 CR4: 00000000003406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff880038d9be80 ffffffff8245a4cd ffffffff8245a15e ffff88003af85c00
 ffff880038d9be98 ffff8800bb1414ac ffff880039f84080 ffff880039f26280
 0000000020004e21 000000002000214e 00000000000003ff bb1414ac00000000
Call Trace:
 [<ffffffff8245a4cd>] rhashtable_compare include/linux/rhashtable.h:514 [inline]
 [<ffffffff8245a4cd>] rhashtable_lookup_fast include/linux/rhashtable.h:548 [inline]
 [<ffffffff8245a4cd>] rds_add_bound net/rds/bind.c:95 [inline]
 [<ffffffff8245a4cd>] rds_bind+0x41d/0xad0 net/rds/bind.c:153
 [<ffffffff820aaa00>] SYSC_bind+0xb0/0xe0 net/socket.c:1377
 [<ffffffff820ab929>] SyS_bind+0x9/0x10 net/socket.c:1363
 [<ffffffff8260c8b6>] entry_SYSCALL_64_fastpath+0x16/0x76
Code: 5d c3 3c 30 74 0b 3c 31 75 f1 31 c0 c6 06 01 5d c3 31 c0 c6 06 00 5d c3 66 2e 0f 1f 84 00 00 00 00 00 55 48 85 d2 48 89 e5 74 33 <0f> b6 07 0f b6 0e 29 c8 75 22 48 83 ea 01 31 c9 eb 15 44 0f b6 
RIP  [<ffffffff818a6c49>] memcmp+0x9/0x40 lib/string.c:770
 RSP <ffff880038d9bde0>
CR2: 0000000000000008
---[ end trace 041f1ed6b60e9e15 ]---