crypto: caam - improve initalization for context state saves

Multiple function in asynchronous hashing use a saved-state block,
a.k.a. struct caam_hash_state, which holds a stash of information
between requests (init/update/final). Certain values in this state
block are loaded for processing using an inline-if, and when this
is done, the potential for uninitialized data can pose conflicts.
Therefore, this patch improves initialization of state data to
prevent false assignments using uninitialized data in the state block.

This patch addresses the following traceback, originating in
ahash_final_ctx(), although a problem like this could certainly
exhibit other symptoms:

kernel BUG at arch/arm/mm/dma-mapping.c:465!
Unable to handle kernel NULL pointer dereference at virtual address 00000000
pgd = 80004000
[00000000] *pgd=00000000
Internal error: Oops: 805 [#1] PREEMPT SMP
Modules linked in:
CPU: 0    Not tainted  (3.0.15-01752-gdd441b9-dirty #40)
PC is at __bug+0x1c/0x28
LR is at __bug+0x18/0x28
pc : [<80043240>]    lr : [<8004323c>]    psr: 60000013
sp : e423fd98  ip : 60000013  fp : 0000001c
r10: e4191b84  r9 : 00000020  r8 : 00000009
r7 : 88005038  r6 : 00000001  r5 : 2d676572  r4 : e4191a60
r3 : 00000000  r2 : 00000001  r1 : 60000093  r0 : 00000033
Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment kernel
Control: 10c53c7d  Table: 1000404a  DAC: 00000015
Process cryptomgr_test (pid: 1306, stack limit = 0xe423e2f0)
Stack: (0xe423fd98 to 0xe4240000)
fd80:                                                       11807fd1 80048544
fda0: 88005000 e4191a00 e5178040 8039dda0 00000000 00000014 2d676572 e4191008
fdc0: 88005018 e4191a60 00100100 e4191a00 00000000 8039ce0c e423fea8 00000007
fde0: e4191a00 e4227000 e5178000 8039ce18 e419183c 80203808 80a94a44 00000006
fe00: 00000000 80207180 00000000 00000006 e423ff08 00000000 00000007 e5178000
fe20: e41918a4 80a949b4 8c4844e2 00000000 00000049 74227000 8c4844e2 00000e90
fe40: 0000000e 74227e90 ffff8c58 80ac29e0 e423fed4 8006a350 8c81625c e423ff5c
fe60: 00008576 e4002500 00000003 00030010 e4002500 00000003 e5180000 e4002500
fe80: e5178000 800e6d24 007fffff 00000000 00000010 e4001280 e4002500 60000013
fea0: 000000d0 804df078 00000000 00000000 00000000 00000000 00000000 00000000
fec0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
fee0: 00000000 00000000 e4227000 e4226000 e4753000 e4752000 e40a5000 e40a4000
ff00: e41e7000 e41e6000 00000000 00000000 00000000 e423ff14 e423ff14 00000000
ff20: 00000400 804f9080 e5178000 e4db0b40 00000000 e4db0b80 0000047c 00000400
ff40: 00000000 8020758c 00000400 ffffffff 0000008a 00000000 e4db0b40 80206e00
ff60: e4049dbc 00000000 00000000 00000003 e423ffa4 80062978 e41a8bfc 00000000
ff80: 00000000 e4049db4 00000013 e4049db0 00000013 00000000 00000000 00000000
ffa0: e4db0b40 e4db0b40 80204cbc 00000013 00000000 00000000 00000000 80204cfc
ffc0: e4049da0 80089544 80040a40 00000000 e4db0b40 00000000 00000000 00000000
ffe0: e423ffe0 e423ffe0 e4049da0 800894c4 80040a40 80040a40 00000000 00000000
[<80043240>] (__bug+0x1c/0x28) from [<80048544>] (___dma_single_dev_to_cpu+0x84)
[<80048544>] (___dma_single_dev_to_cpu+0x84/0x94) from [<8039dda0>] (ahash_fina)
[<8039dda0>] (ahash_final_ctx+0x180/0x428) from [<8039ce18>] (ahash_final+0xc/0)
[<8039ce18>] (ahash_final+0xc/0x10) from [<80203808>] (crypto_ahash_op+0x28/0xc)
[<80203808>] (crypto_ahash_op+0x28/0xc0) from [<80207180>] (test_hash+0x214/0x5)
[<80207180>] (test_hash+0x214/0x5b8) from [<8020758c>] (alg_test_hash+0x68/0x8c)
[<8020758c>] (alg_test_hash+0x68/0x8c) from [<80206e00>] (alg_test+0x7c/0x1b8)
[<80206e00>] (alg_test+0x7c/0x1b8) from [<80204cfc>] (cryptomgr_test+0x40/0x48)
[<80204cfc>] (cryptomgr_test+0x40/0x48) from [<80089544>] (kthread+0x80/0x88)
[<80089544>] (kthread+0x80/0x88) from [<80040a40>] (kernel_thread_exit+0x0/0x8)
Code: e59f0010 e1a01003 eb126a8d e3a03000 (e5833000)
---[ end trace d52a403a1d1eaa86 ]---

Cc: stable@vger.kernel.org
Signed-off-by: Steve Cornelius <steve.cornelius@freescale.com>
Signed-off-by: Victoria Milhoan <vicki.milhoan@freescale.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/caam/caamhash.c

@@ -1544,6 +1544,8 @@ static int ahash_init(struct ahash_request *req)
 
 	state->current_buf = 0;
 	state->buf_dma = 0;
+	state->buflen_0 = 0;
+	state->buflen_1 = 0;
 
 	return 0;
 }