audit: type=1400 audit(1513095920.079:41): avc:  denied  { accept } for  pid=4089 comm="syz-executor1" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=1
BUG: unable to handle kernel NULL pointer dereference at 0000000000000074
IP: virt_to_cache mm/slab.c:400 [inline]
IP: kfree+0xb2/0x250 mm/slab.c:3802
PGD 1d9a47067 P4D 1d9a47067 PUD 1ce449067 PMD 0 
Oops: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 4090 Comm: syz-executor4 Not tainted 4.15.0-rc2+ #150
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:virt_to_cache mm/slab.c:400 [inline]
RIP: 0010:kfree+0xb2/0x250 mm/slab.c:3802
RSP: 0018:ffff8801d389f780 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff8801d389f948 RCX: ffffffffffffffff
RDX: ffffea00074e27c0 RSI: 0000000000000000 RDI: ffff8801d389f948
RBP: ffff8801d389f7a0 R08: ffff8801d39d0b40 R09: ffff8801d3a0f3c0
R10: ffff8801d389f950 R11: 0000000000000108 R12: 0000000000000282
R13: 0000000000000000 R14: ffff8801d389f948 R15: ffff8801d389f8b0
FS:  00007f8992009700(0000) GS:ffff8801db400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000074 CR3: 00000001d575e000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 blkcipher_walk_done+0x72b/0xde0 crypto/blkcipher.c:139
 encrypt+0x20e/0x540 arch/x86/crypto/salsa20_glue.c:79
 skcipher_crypt_blkcipher crypto/skcipher.c:622 [inline]
 skcipher_decrypt_blkcipher+0x213/0x310 crypto/skcipher.c:640
 crypto_skcipher_decrypt include/crypto/skcipher.h:463 [inline]
 _skcipher_recvmsg crypto/algif_skcipher.c:144 [inline]
 skcipher_recvmsg+0xa54/0xf20 crypto/algif_skcipher.c:165
 sock_recvmsg_nosec net/socket.c:809 [inline]
 sock_recvmsg+0xc9/0x110 net/socket.c:816
 ___sys_recvmsg+0x29b/0x630 net/socket.c:2185
 __sys_recvmsg+0xe2/0x210 net/socket.c:2230
 SYSC_recvmsg net/socket.c:2242 [inline]
 SyS_recvmsg+0x2d/0x50 net/socket.c:2237
 entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x452a39
RSP: 002b:00007f8992008c58 EFLAGS: 00000212 ORIG_RAX: 000000000000002f
RAX: ffffffffffffffda RBX: 0000000000758190 RCX: 0000000000452a39
RDX: 0000000000000000 RSI: 0000000020444fc8 RDI: 000000000000001c
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006ee0b8
R13: 00000000ffffffff R14: 00007f89920096d4 R15: 0000000000000020
Code: c2 48 b8 00 00 00 00 00 ea ff ff 48 89 df 48 c1 ea 0c 48 c1 e2 06 48 01 c2 48 8b 42 20 48 8d 48 ff a8 01 48 0f 45 d1 4c 8b 6a 30 <49> 63 75 74 e8 05 74 af ff 48 89 de 4c 89 ef 4c 8b 75 08 e8 06 
RIP: virt_to_cache mm/slab.c:400 [inline] RSP: ffff8801d389f780
RIP: kfree+0xb2/0x250 mm/slab.c:3802 RSP: ffff8801d389f780
CR2: 0000000000000074
---[ end trace 00476670e0f8c038 ]---