BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
IP: scatterwalk_start include/crypto/scatterwalk.h:85 [inline]
IP: scatterwalk_pagedone include/crypto/scatterwalk.h:111 [inline]
IP: scatterwalk_copychunks+0x16e/0x200 crypto/scatterwalk.c:55
PGD 1e3939067 P4D 1e3939067 PUD 1e5cfb067 PMD 0 
Oops: 0000 [#1] SMP
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 3808 Comm: syz-executor7 Not tainted 4.15.0-rc3-next-20171214+ #67
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:scatterwalk_start include/crypto/scatterwalk.h:85 [inline]
RIP: 0010:scatterwalk_pagedone include/crypto/scatterwalk.h:111 [inline]
RIP: 0010:scatterwalk_copychunks+0x16e/0x200 crypto/scatterwalk.c:55
RSP: 0018:ffffc90000ddf7b0 EFLAGS: 00010216
RAX: 0000000000000000 RBX: 0000000000000041 RCX: ffffffff81739c3b
RDX: 00000000000003a6 RSI: ffffc900018c9000 RDI: ffff8801e63495a0
RBP: ffffc90000ddf7e8 R08: 000000009a4c1b28 R09: 000000004b90a3fa
R10: 0000000000000000 R11: ffff8801e38da040 R12: 0000000000000041
R13: ffff8801e63495a0 R14: 000000000000000f R15: ffffc90000ddf8f0
FS:  00007ffb3c0b8700(0000) GS:ffff88021fd00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000008 CR3: 00000001e385b000 CR4: 00000000001426e0
DR0: 0000000020000008 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 blkcipher_next_slow crypto/blkcipher.c:174 [inline]
 blkcipher_walk_next+0x4c0/0x590 crypto/blkcipher.c:254
 blkcipher_walk_done+0x1a8/0x360 crypto/blkcipher.c:132
 glue_ctr_crypt_128bit+0x1ef/0x390 arch/x86/crypto/glue_helper.c:289
 ctr_crypt+0x34/0x40 arch/x86/crypto/serpent_avx2_glue.c:168
 __ablk_encrypt+0x43/0x50 crypto/ablk_helper.c:61
 ablk_encrypt+0xd9/0xf0 crypto/ablk_helper.c:81
 skcipher_crypt_ablkcipher crypto/skcipher.c:712 [inline]
 skcipher_decrypt_ablkcipher+0x6d/0x70 crypto/skcipher.c:730
 crypto_skcipher_decrypt include/crypto/skcipher.h:463 [inline]
 chacha_decrypt crypto/chacha20poly1305.c:152 [inline]
 poly_tail_continue+0x128/0x170 crypto/chacha20poly1305.c:167
 poly_tail+0x128/0x160 crypto/chacha20poly1305.c:201
 poly_cipherpad+0x126/0x160 crypto/chacha20poly1305.c:231
 poly_cipher+0xb9/0xd0 crypto/chacha20poly1305.c:262
 poly_adpad+0x126/0x160 crypto/chacha20poly1305.c:292
 poly_ad+0x7d/0x90 crypto/chacha20poly1305.c:316
 poly_setkey+0x107/0x130 crypto/chacha20poly1305.c:343
 poly_init+0x5a/0x70 crypto/chacha20poly1305.c:366
 poly_genkey+0x181/0x1c0 crypto/chacha20poly1305.c:406
 chachapoly_decrypt+0x21/0x30 crypto/chacha20poly1305.c:488
 crypto_aead_decrypt include/crypto/aead.h:362 [inline]
 _aead_recvmsg crypto/algif_aead.c:314 [inline]
 aead_recvmsg+0x843/0x8c0 crypto/algif_aead.c:335
 sock_recvmsg_nosec net/socket.c:809 [inline]
 sock_recvmsg+0x4d/0x70 net/socket.c:816
 ___sys_recvmsg+0x118/0x2b0 net/socket.c:2185
 __sys_recvmsg+0x4d/0x90 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:00007ffb3c0b7c58 EFLAGS: 00000212 ORIG_RAX: 000000000000002f
RAX: ffffffffffffffda RBX: 00007ffb3c0b8700 RCX: 0000000000452a39
RDX: 0000000000000002 RSI: 000000002022efc8 RDI: 0000000000000017
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 0000000000000000
R13: 0000000000a6f7ff R14: 00007ffb3c0b89c0 R15: 0000000000000000
Code: 4d 8b 2f 4c 01 65 c8 4d 29 e6 45 8b 65 0c 45 03 65 08 44 39 e3 0f 82 d4 fe ff ff e8 bd 25 c4 ff 4c 89 ef e8 85 1e 0c 00 49 89 07 <8b> 58 08 49 89 c5 41 89 5f 08 44 8b 60 0c 44 03 60 08 e9 ad fe 
RIP: scatterwalk_start include/crypto/scatterwalk.h:85 [inline] RSP: ffffc90000ddf7b0
RIP: scatterwalk_pagedone include/crypto/scatterwalk.h:111 [inline] RSP: ffffc90000ddf7b0
RIP: scatterwalk_copychunks+0x16e/0x200 crypto/scatterwalk.c:55 RSP: ffffc90000ddf7b0
CR2: 0000000000000008
---[ end trace 0e31814ed03f82e6 ]---