[CRYPTO] gcm: Put abreq in private context instead of on stack

The abreq structure is currently allocated on the stack.  This is broken
if the underlying algorithm is asynchronous.  This patch changes it so
that it's taken from the private context instead which has been enlarged
accordingly.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/gcm.c

@@ -40,6 +40,7 @@ struct crypto_gcm_req_priv_ctx {
 	u8 iauth_tag[16];
 	u8 counter[16];
 	struct crypto_gcm_ghash_ctx ghash;
+	struct ablkcipher_request abreq;
 };
 
 static void crypto_gcm_ghash_init(struct crypto_gcm_ghash_ctx *ctx, u32 flags,
@@ -280,16 +281,17 @@ static void crypto_gcm_encrypt_done(struct crypto_async_request *areq, int err)
 
 static int crypto_gcm_encrypt(struct aead_request *req)
 {
-	struct ablkcipher_request abreq;
+	struct crypto_gcm_req_priv_ctx *pctx = aead_request_ctx(req);
+	struct ablkcipher_request *abreq = &pctx->abreq;
 	int err = 0;
 
-	err = crypto_gcm_init_crypt(&abreq, req, req->cryptlen,
+	err = crypto_gcm_init_crypt(abreq, req, req->cryptlen,
 				    crypto_gcm_encrypt_done);
 	if (err)
 		return err;
 
 	if (req->cryptlen) {
-		err = crypto_ablkcipher_encrypt(&abreq);
+		err = crypto_ablkcipher_encrypt(abreq);
 		if (err)
 			return err;
 	}
@@ -304,9 +306,9 @@ static void crypto_gcm_decrypt_done(struct crypto_async_request *areq, int err)
 
 static int crypto_gcm_decrypt(struct aead_request *req)
 {
-	struct ablkcipher_request abreq;
 	struct crypto_aead *aead = crypto_aead_reqtfm(req);
 	struct crypto_gcm_req_priv_ctx *pctx = aead_request_ctx(req);
+	struct ablkcipher_request *abreq = &pctx->abreq;
 	u8 *auth_tag = pctx->auth_tag;
 	u8 *iauth_tag = pctx->iauth_tag;
 	struct crypto_gcm_ghash_ctx *ghash = &pctx->ghash;
@@ -318,7 +320,7 @@ static int crypto_gcm_decrypt(struct aead_request *req)
 		return -EINVAL;
 	cryptlen -= authsize;
 
-	err = crypto_gcm_init_crypt(&abreq, req, cryptlen,
+	err = crypto_gcm_init_crypt(abreq, req, cryptlen,
 				    crypto_gcm_decrypt_done);
 	if (err)
 		return err;
@@ -330,7 +332,7 @@ static int crypto_gcm_decrypt(struct aead_request *req)
 	if (memcmp(iauth_tag, auth_tag, authsize))
 		return -EBADMSG;
 
-	return crypto_ablkcipher_decrypt(&abreq);
+	return crypto_ablkcipher_decrypt(abreq);
 }
 
 static int crypto_gcm_init_tfm(struct crypto_tfm *tfm)
@@ -353,7 +355,9 @@ static int crypto_gcm_init_tfm(struct crypto_tfm *tfm)
 	align = max_t(unsigned long, crypto_ablkcipher_alignmask(ctr),
 		      __alignof__(u32) - 1);
 	align &= ~(crypto_tfm_ctx_alignment() - 1);
-	tfm->crt_aead.reqsize = align + sizeof(struct crypto_gcm_req_priv_ctx);
+	tfm->crt_aead.reqsize = align +
+				sizeof(struct crypto_gcm_req_priv_ctx) +
+				crypto_ablkcipher_reqsize(ctr);
 
 	return 0;
 }