crypto: sun8i-ce - Fix use after free in unprepare

In the Linux kernel, the following vulnerability has been resolved:

crypto: sun8i-ce - Fix use after free in unprepare

sun8i_ce_cipher_unprepare should be called before
crypto_finalize_skcipher_request, because client callbacks may
immediately free memory, that isn't needed anymore. But it will be
used by unprepare after free. Before removing prepare/unprepare
callbacks it was handled by crypto engine in crypto_finalize_request.

Usually that results in a pointer dereference problem during a in
crypto selftest.
Unable to handle kernel NULL pointer dereference at
virtual address 0000000000000030
Mem abort info:
ESR = 0x0000000096000004
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x04: level 0 translation fault
Data abort info:
ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
CM = 0, WnR = 0, TnD = 0, TagAccess = 0
GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
user pgtable: 4k pages, 48-bit VAs, pgdp=000000004716d000
[0000000000000030] pgd=0000000000000000, p4d=0000000000000000
Internal error: Oops: 0000000096000004 [#1] SMP

This problem is detected by KASAN as well.
==================================================================
BUG: KASAN: slab-use-after-free in sun8i_ce_cipher_do_one+0x6e8/0xf80 [sun8i_ce]
Read of size 8 at addr ffff00000dcdc040 by task 1c15000.crypto-/373

Hardware name: Pine64 PinePhone (1.2) (DT)
Call trace:
dump_backtrace+0x9c/0x128
show_stack+0x20/0x38
dump_stack_lvl+0x48/0x60
print_report+0xf8/0x5d8
kasan_report+0x90/0xd0
__asan_load8+0x9c/0xc0
sun8i_ce_cipher_do_one+0x6e8/0xf80 [sun8i_ce]
crypto_pump_work+0x354/0x620 [crypto_engine]
kthread_worker_fn+0x244/0x498
kthread+0x168/0x178
ret_from_fork+0x10/0x20

Allocated by task 379:
kasan_save_stack+0x3c/0x68
kasan_set_track+0x2c/0x40
kasan_save_alloc_info+0x24/0x38
__kasan_kmalloc+0xd4/0xd8
__kmalloc+0x74/0x1d0
alg_test_skcipher+0x90/0x1f0
alg_test+0x24c/0x830
cryptomgr_test+0x38/0x60
kthread+0x168/0x178
ret_from_fork+0x10/0x20

Freed by task 379:
kasan_save_stack+0x3c/0x68
kasan_set_track+0x2c/0x40
kasan_save_free_info+0x38/0x60
__kasan_slab_free+0x100/0x170
slab_free_freelist_hook+0xd4/0x1e8
__kmem_cache_free+0x15c/0x290
kfree+0x74/0x100
kfree_sensitive+0x80/0xb0
alg_test_skcipher+0x12c/0x1f0
alg_test+0x24c/0x830
cryptomgr_test+0x38/0x60
kthread+0x168/0x178
ret_from_fork+0x10/0x20

The buggy address belongs to the object at ffff00000dcdc000
which belongs to the cache kmalloc-256 of size 256
The buggy address is located 64 bytes inside of
freed 256-byte region [ffff00000dcdc000, ffff00000dcdc100)