[CRYPTO] authenc: Fix async crypto crash in crypto_authenc_genicv()

crypto_authenc_givencrypt_done uses req->data as struct aead_givcrypt_request,
while it really points to a struct aead_request, causing this crash:

BUG: unable to handle kernel paging request at 6b6b6b6b
IP: [<dc87517b>] :authenc:crypto_authenc_genicv+0x23/0x109
*pde = 00000000
Oops: 0000 [#1] PREEMPT DEBUG_PAGEALLOC
Modules linked in: hifn_795x authenc esp4 aead xfrm4_mode_tunnel sha1_generic hmac crypto_hash]

Pid: 3074, comm: ping Not tainted (2.6.25 #4)
EIP: 0060:[<dc87517b>] EFLAGS: 00010296 CPU: 0
EIP is at crypto_authenc_genicv+0x23/0x109 [authenc]
EAX: daa04690 EBX: daa046e0 ECX: dab0a100 EDX: daa046b0
ESI: 6b6b6b6b EDI: dc872054 EBP: c033ff60 ESP: c033ff0c
 DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068
Process ping (pid: 3074, ti=c033f000 task=db883a80 task.ti=dab6c000)
Stack: 00000000 daa046b0 c0215a3e daa04690 dab0a100 00000000 ffffffff db9fd7f0
       dba208c0 dbbb1720 00000001 daa04720 00000001 c033ff54 c0119ca9 dc852a75
       c033ff60 c033ff60 daa046e0 00000000 00000001 c033ff6c dc87527b 00000001
Call Trace:
 [<c0215a3e>] ? dev_alloc_skb+0x14/0x29
 [<c0119ca9>] ? printk+0x15/0x17
 [<dc87527b>] ? crypto_authenc_givencrypt_done+0x1a/0x27 [authenc]
 [<dc850cca>] ? hifn_process_ready+0x34a/0x352 [hifn_795x]
 [<dc8353c7>] ? rhine_napipoll+0x3f2/0x3fd [via_rhine]
 [<dc851a56>] ? hifn_check_for_completion+0x4d/0xa6 [hifn_795x]
 [<dc851ab9>] ? hifn_tasklet_callback+0xa/0xc [hifn_795x]
 [<c011d046>] ? tasklet_action+0x3f/0x66
 [<c011d230>] ? __do_softirq+0x38/0x7a
 [<c0105a5f>] ? do_softirq+0x3e/0x71
 [<c011d17c>] ? irq_exit+0x2c/0x65
 [<c010e0c0>] ? smp_apic_timer_interrupt+0x5f/0x6a
 [<c01042e4>] ? apic_timer_interrupt+0x28/0x30
 [<dc851640>] ? hifn_handle_req+0x44a/0x50d [hifn_795x]
 ...

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/authenc.c

@@ -217,9 +217,10 @@ static void crypto_authenc_givencrypt_done(struct crypto_async_request *req,
 					   int err)
 {
 	if (!err) {
-		struct aead_givcrypt_request *greq = req->data;
+		struct aead_request *areq = req->data;
+		struct skcipher_givcrypt_request *greq = aead_request_ctx(areq);
 
-		err = crypto_authenc_genicv(&greq->areq, greq->giv, 0);
+		err = crypto_authenc_genicv(areq, greq->giv, 0);
 	}
 
 	aead_request_complete(req->data, err);