diff mbox series

[v5,10/14] crypto: caam - fix MDHA key derivation for certain user key lengths

Message ID 1564578495-9883-11-git-send-email-iuliana.prodan@nxp.com (mailing list archive)
State Accepted
Delegated to: Herbert Xu
Headers show
Series crypto: caam - fixes for kernel v5.3 | expand

Commit Message

Iuliana Prodan July 31, 2019, 1:08 p.m. UTC 
From: Horia Geantă <horia.geanta@nxp.com>

Fuzz testing uncovered an issue when |user key| > |derived key|.
Derived key generation has to be fixed in two cases:

1. Era >= 6 (DKP is available)
DKP cannot be used with immediate input key if |user key| > |derived key|,
since the resulting descriptor (after DKP execution) would be invalid -
having a few bytes from user key left in descriptor buffer
as incorrect opcodes.

Fix DKP usage both in standalone hmac and in authenc algorithms.
For authenc the logic is simplified, by always storing both virtual
and dma key addresses.

2. Era < 6
The same case (|user key| > |derived key|) fails when DKP
is not available.
Make sure gen_split_key() dma maps max(|user key|, |derived key|),
since this is an in-place (bidirectional) operation.

Signed-off-by: Horia Geantă <horia.geanta@nxp.com>
Reviewed-by: Iuliana Prodan <iuliana.prodan@nxp.com>
---
 drivers/crypto/caam/caamalg.c     | 42 +++++++-----------------
 drivers/crypto/caam/caamalg_qi.c  | 42 +++++++-----------------
 drivers/crypto/caam/caamalg_qi2.c | 67 +++++++++++++++++++++++++++------------
 drivers/crypto/caam/caamhash.c    | 53 ++++++++++++++++++++++---------
 drivers/crypto/caam/desc_constr.h | 24 ++++++++++----
 drivers/crypto/caam/key_gen.c     |  9 +++---
 6 files changed, 132 insertions(+), 105 deletions(-)
diff mbox series

Patch

diff --git a/drivers/crypto/caam/caamalg.c b/drivers/crypto/caam/caamalg.c
index 21e30de..947ba8e 100644
--- a/drivers/crypto/caam/caamalg.c
+++ b/drivers/crypto/caam/caamalg.c
@@ -205,6 +205,18 @@  static int aead_set_sh_desc(struct crypto_aead *aead)
 				ctx->cdata.keylen - CTR_RFC3686_NONCE_SIZE);
 	}
 
+	/*
+	 * In case |user key| > |derived key|, using DKP<imm,imm>
+	 * would result in invalid opcodes (last bytes of user key) in
+	 * the resulting descriptor. Use DKP<ptr,imm> instead => both
+	 * virtual and dma key addresses are needed.
+	 */
+	ctx->adata.key_virt = ctx->key;
+	ctx->adata.key_dma = ctx->key_dma;
+
+	ctx->cdata.key_virt = ctx->key + ctx->adata.keylen_pad;
+	ctx->cdata.key_dma = ctx->key_dma + ctx->adata.keylen_pad;
+
 	data_len[0] = ctx->adata.keylen_pad;
 	data_len[1] = ctx->cdata.keylen;
 
@@ -221,16 +233,6 @@  static int aead_set_sh_desc(struct crypto_aead *aead)
 			      ARRAY_SIZE(data_len)) < 0)
 		return -EINVAL;
 
-	if (inl_mask & 1)
-		ctx->adata.key_virt = ctx->key;
-	else
-		ctx->adata.key_dma = ctx->key_dma;
-
-	if (inl_mask & 2)
-		ctx->cdata.key_virt = ctx->key + ctx->adata.keylen_pad;
-	else
-		ctx->cdata.key_dma = ctx->key_dma + ctx->adata.keylen_pad;
-
 	ctx->adata.key_inline = !!(inl_mask & 1);
 	ctx->cdata.key_inline = !!(inl_mask & 2);
 
@@ -253,16 +255,6 @@  static int aead_set_sh_desc(struct crypto_aead *aead)
 			      ARRAY_SIZE(data_len)) < 0)
 		return -EINVAL;
 
-	if (inl_mask & 1)
-		ctx->adata.key_virt = ctx->key;
-	else
-		ctx->adata.key_dma = ctx->key_dma;
-
-	if (inl_mask & 2)
-		ctx->cdata.key_virt = ctx->key + ctx->adata.keylen_pad;
-	else
-		ctx->cdata.key_dma = ctx->key_dma + ctx->adata.keylen_pad;
-
 	ctx->adata.key_inline = !!(inl_mask & 1);
 	ctx->cdata.key_inline = !!(inl_mask & 2);
 
@@ -287,16 +279,6 @@  static int aead_set_sh_desc(struct crypto_aead *aead)
 			      ARRAY_SIZE(data_len)) < 0)
 		return -EINVAL;
 
-	if (inl_mask & 1)
-		ctx->adata.key_virt = ctx->key;
-	else
-		ctx->adata.key_dma = ctx->key_dma;
-
-	if (inl_mask & 2)
-		ctx->cdata.key_virt = ctx->key + ctx->adata.keylen_pad;
-	else
-		ctx->cdata.key_dma = ctx->key_dma + ctx->adata.keylen_pad;
-
 	ctx->adata.key_inline = !!(inl_mask & 1);
 	ctx->cdata.key_inline = !!(inl_mask & 2);
 
diff --git a/drivers/crypto/caam/caamalg_qi.c b/drivers/crypto/caam/caamalg_qi.c
index e63b2f7..59b59f5 100644
--- a/drivers/crypto/caam/caamalg_qi.c
+++ b/drivers/crypto/caam/caamalg_qi.c
@@ -105,6 +105,18 @@  static int aead_set_sh_desc(struct crypto_aead *aead)
 				ctx->cdata.keylen - CTR_RFC3686_NONCE_SIZE);
 	}
 
+	/*
+	 * In case |user key| > |derived key|, using DKP<imm,imm> would result
+	 * in invalid opcodes (last bytes of user key) in the resulting
+	 * descriptor. Use DKP<ptr,imm> instead => both virtual and dma key
+	 * addresses are needed.
+	 */
+	ctx->adata.key_virt = ctx->key;
+	ctx->adata.key_dma = ctx->key_dma;
+
+	ctx->cdata.key_virt = ctx->key + ctx->adata.keylen_pad;
+	ctx->cdata.key_dma = ctx->key_dma + ctx->adata.keylen_pad;
+
 	data_len[0] = ctx->adata.keylen_pad;
 	data_len[1] = ctx->cdata.keylen;
 
@@ -118,16 +130,6 @@  static int aead_set_sh_desc(struct crypto_aead *aead)
 			      ARRAY_SIZE(data_len)) < 0)
 		return -EINVAL;
 
-	if (inl_mask & 1)
-		ctx->adata.key_virt = ctx->key;
-	else
-		ctx->adata.key_dma = ctx->key_dma;
-
-	if (inl_mask & 2)
-		ctx->cdata.key_virt = ctx->key + ctx->adata.keylen_pad;
-	else
-		ctx->cdata.key_dma = ctx->key_dma + ctx->adata.keylen_pad;
-
 	ctx->adata.key_inline = !!(inl_mask & 1);
 	ctx->cdata.key_inline = !!(inl_mask & 2);
 
@@ -143,16 +145,6 @@  static int aead_set_sh_desc(struct crypto_aead *aead)
 			      ARRAY_SIZE(data_len)) < 0)
 		return -EINVAL;
 
-	if (inl_mask & 1)
-		ctx->adata.key_virt = ctx->key;
-	else
-		ctx->adata.key_dma = ctx->key_dma;
-
-	if (inl_mask & 2)
-		ctx->cdata.key_virt = ctx->key + ctx->adata.keylen_pad;
-	else
-		ctx->cdata.key_dma = ctx->key_dma + ctx->adata.keylen_pad;
-
 	ctx->adata.key_inline = !!(inl_mask & 1);
 	ctx->cdata.key_inline = !!(inl_mask & 2);
 
@@ -171,16 +163,6 @@  static int aead_set_sh_desc(struct crypto_aead *aead)
 			      ARRAY_SIZE(data_len)) < 0)
 		return -EINVAL;
 
-	if (inl_mask & 1)
-		ctx->adata.key_virt = ctx->key;
-	else
-		ctx->adata.key_dma = ctx->key_dma;
-
-	if (inl_mask & 2)
-		ctx->cdata.key_virt = ctx->key + ctx->adata.keylen_pad;
-	else
-		ctx->cdata.key_dma = ctx->key_dma + ctx->adata.keylen_pad;
-
 	ctx->adata.key_inline = !!(inl_mask & 1);
 	ctx->cdata.key_inline = !!(inl_mask & 2);
 
diff --git a/drivers/crypto/caam/caamalg_qi2.c b/drivers/crypto/caam/caamalg_qi2.c
index d112975..df7513b 100644
--- a/drivers/crypto/caam/caamalg_qi2.c
+++ b/drivers/crypto/caam/caamalg_qi2.c
@@ -198,6 +198,18 @@  static int aead_set_sh_desc(struct crypto_aead *aead)
 				ctx->cdata.keylen - CTR_RFC3686_NONCE_SIZE);
 	}
 
+	/*
+	 * In case |user key| > |derived key|, using DKP<imm,imm> would result
+	 * in invalid opcodes (last bytes of user key) in the resulting
+	 * descriptor. Use DKP<ptr,imm> instead => both virtual and dma key
+	 * addresses are needed.
+	 */
+	ctx->adata.key_virt = ctx->key;
+	ctx->adata.key_dma = ctx->key_dma;
+
+	ctx->cdata.key_virt = ctx->key + ctx->adata.keylen_pad;
+	ctx->cdata.key_dma = ctx->key_dma + ctx->adata.keylen_pad;
+
 	data_len[0] = ctx->adata.keylen_pad;
 	data_len[1] = ctx->cdata.keylen;
 
@@ -209,16 +221,6 @@  static int aead_set_sh_desc(struct crypto_aead *aead)
 			      ARRAY_SIZE(data_len)) < 0)
 		return -EINVAL;
 
-	if (inl_mask & 1)
-		ctx->adata.key_virt = ctx->key;
-	else
-		ctx->adata.key_dma = ctx->key_dma;
-
-	if (inl_mask & 2)
-		ctx->cdata.key_virt = ctx->key + ctx->adata.keylen_pad;
-	else
-		ctx->cdata.key_dma = ctx->key_dma + ctx->adata.keylen_pad;
-
 	ctx->adata.key_inline = !!(inl_mask & 1);
 	ctx->cdata.key_inline = !!(inl_mask & 2);
 
@@ -247,16 +249,6 @@  static int aead_set_sh_desc(struct crypto_aead *aead)
 			      ARRAY_SIZE(data_len)) < 0)
 		return -EINVAL;
 
-	if (inl_mask & 1)
-		ctx->adata.key_virt = ctx->key;
-	else
-		ctx->adata.key_dma = ctx->key_dma;
-
-	if (inl_mask & 2)
-		ctx->cdata.key_virt = ctx->key + ctx->adata.keylen_pad;
-	else
-		ctx->cdata.key_dma = ctx->key_dma + ctx->adata.keylen_pad;
-
 	ctx->adata.key_inline = !!(inl_mask & 1);
 	ctx->cdata.key_inline = !!(inl_mask & 2);
 
@@ -2998,6 +2990,7 @@  enum hash_optype {
 /**
  * caam_hash_ctx - ahash per-session context
  * @flc: Flow Contexts array
+ * @key: authentication key
  * @flc_dma: I/O virtual addresses of the Flow Contexts
  * @dev: dpseci device
  * @ctx_len: size of Context Register
@@ -3005,6 +2998,7 @@  enum hash_optype {
  */
 struct caam_hash_ctx {
 	struct caam_flc flc[HASH_NUM_OP];
+	u8 key[CAAM_MAX_HASH_BLOCK_SIZE] ____cacheline_aligned;
 	dma_addr_t flc_dma[HASH_NUM_OP];
 	struct device *dev;
 	int ctx_len;
@@ -3305,6 +3299,19 @@  static int ahash_setkey(struct crypto_ahash *ahash, const u8 *key,
 	ctx->adata.key_virt = key;
 	ctx->adata.key_inline = true;
 
+	/*
+	 * In case |user key| > |derived key|, using DKP<imm,imm> would result
+	 * in invalid opcodes (last bytes of user key) in the resulting
+	 * descriptor. Use DKP<ptr,imm> instead => both virtual and dma key
+	 * addresses are needed.
+	 */
+	if (keylen > ctx->adata.keylen_pad) {
+		memcpy(ctx->key, key, keylen);
+		dma_sync_single_for_device(ctx->dev, ctx->adata.key_dma,
+					   ctx->adata.keylen_pad,
+					   DMA_TO_DEVICE);
+	}
+
 	ret = ahash_set_sh_desc(ahash);
 	kfree(hashed_key);
 	return ret;
@@ -4535,11 +4542,27 @@  static int caam_hash_cra_init(struct crypto_tfm *tfm)
 
 	ctx->dev = caam_hash->dev;
 
+	if (alg->setkey) {
+		ctx->adata.key_dma = dma_map_single_attrs(ctx->dev, ctx->key,
+							  ARRAY_SIZE(ctx->key),
+							  DMA_TO_DEVICE,
+							  DMA_ATTR_SKIP_CPU_SYNC);
+		if (dma_mapping_error(ctx->dev, ctx->adata.key_dma)) {
+			dev_err(ctx->dev, "unable to map key\n");
+			return -ENOMEM;
+		}
+	}
+
 	dma_addr = dma_map_single_attrs(ctx->dev, ctx->flc, sizeof(ctx->flc),
 					DMA_BIDIRECTIONAL,
 					DMA_ATTR_SKIP_CPU_SYNC);
 	if (dma_mapping_error(ctx->dev, dma_addr)) {
 		dev_err(ctx->dev, "unable to map shared descriptors\n");
+		if (ctx->adata.key_dma)
+			dma_unmap_single_attrs(ctx->dev, ctx->adata.key_dma,
+					       ARRAY_SIZE(ctx->key),
+					       DMA_TO_DEVICE,
+					       DMA_ATTR_SKIP_CPU_SYNC);
 		return -ENOMEM;
 	}
 
@@ -4565,6 +4588,10 @@  static void caam_hash_cra_exit(struct crypto_tfm *tfm)
 
 	dma_unmap_single_attrs(ctx->dev, ctx->flc_dma[0], sizeof(ctx->flc),
 			       DMA_BIDIRECTIONAL, DMA_ATTR_SKIP_CPU_SYNC);
+	if (ctx->adata.key_dma)
+		dma_unmap_single_attrs(ctx->dev, ctx->adata.key_dma,
+				       ARRAY_SIZE(ctx->key), DMA_TO_DEVICE,
+				       DMA_ATTR_SKIP_CPU_SYNC);
 }
 
 static struct caam_hash_alg *caam_hash_alloc(struct device *dev,
diff --git a/drivers/crypto/caam/caamhash.c b/drivers/crypto/caam/caamhash.c
index d19373e..ed1931f 100644
--- a/drivers/crypto/caam/caamhash.c
+++ b/drivers/crypto/caam/caamhash.c
@@ -96,6 +96,7 @@  struct caam_hash_ctx {
 	dma_addr_t sh_desc_fin_dma;
 	dma_addr_t sh_desc_digest_dma;
 	enum dma_data_direction dir;
+	enum dma_data_direction key_dir;
 	struct device *jrdev;
 	int ctx_len;
 	struct alginfo adata;
@@ -476,6 +477,18 @@  static int ahash_setkey(struct crypto_ahash *ahash,
 			goto bad_free_key;
 
 		memcpy(ctx->key, key, keylen);
+
+		/*
+		 * In case |user key| > |derived key|, using DKP<imm,imm>
+		 * would result in invalid opcodes (last bytes of user key) in
+		 * the resulting descriptor. Use DKP<ptr,imm> instead => both
+		 * virtual and dma key addresses are needed.
+		 */
+		if (keylen > ctx->adata.keylen_pad)
+			dma_sync_single_for_device(ctx->jrdev,
+						   ctx->adata.key_dma,
+						   ctx->adata.keylen_pad,
+						   DMA_TO_DEVICE);
 	} else {
 		ret = gen_split_key(ctx->jrdev, ctx->key, &ctx->adata, key,
 				    keylen, CAAM_MAX_HASH_KEY_SIZE);
@@ -1825,40 +1838,50 @@  static int caam_hash_cra_init(struct crypto_tfm *tfm)
 
 	if (is_xcbc_aes(caam_hash->alg_type)) {
 		ctx->dir = DMA_TO_DEVICE;
+		ctx->key_dir = DMA_BIDIRECTIONAL;
 		ctx->adata.algtype = OP_TYPE_CLASS1_ALG | caam_hash->alg_type;
 		ctx->ctx_len = 48;
-
-		ctx->adata.key_dma = dma_map_single_attrs(ctx->jrdev, ctx->key,
-							  ARRAY_SIZE(ctx->key),
-							  DMA_BIDIRECTIONAL,
-							  DMA_ATTR_SKIP_CPU_SYNC);
-		if (dma_mapping_error(ctx->jrdev, ctx->adata.key_dma)) {
-			dev_err(ctx->jrdev, "unable to map key\n");
-			caam_jr_free(ctx->jrdev);
-			return -ENOMEM;
-		}
 	} else if (is_cmac_aes(caam_hash->alg_type)) {
 		ctx->dir = DMA_TO_DEVICE;
+		ctx->key_dir = DMA_NONE;
 		ctx->adata.algtype = OP_TYPE_CLASS1_ALG | caam_hash->alg_type;
 		ctx->ctx_len = 32;
 	} else {
-		ctx->dir = priv->era >= 6 ? DMA_BIDIRECTIONAL : DMA_TO_DEVICE;
+		if (priv->era >= 6) {
+			ctx->dir = DMA_BIDIRECTIONAL;
+			ctx->key_dir = alg->setkey ? DMA_TO_DEVICE : DMA_NONE;
+		} else {
+			ctx->dir = DMA_TO_DEVICE;
+			ctx->key_dir = DMA_NONE;
+		}
 		ctx->adata.algtype = OP_TYPE_CLASS2_ALG | caam_hash->alg_type;
 		ctx->ctx_len = runninglen[(ctx->adata.algtype &
 					   OP_ALG_ALGSEL_SUBMASK) >>
 					  OP_ALG_ALGSEL_SHIFT];
 	}
 
+	if (ctx->key_dir != DMA_NONE) {
+		ctx->adata.key_dma = dma_map_single_attrs(ctx->jrdev, ctx->key,
+							  ARRAY_SIZE(ctx->key),
+							  ctx->key_dir,
+							  DMA_ATTR_SKIP_CPU_SYNC);
+		if (dma_mapping_error(ctx->jrdev, ctx->adata.key_dma)) {
+			dev_err(ctx->jrdev, "unable to map key\n");
+			caam_jr_free(ctx->jrdev);
+			return -ENOMEM;
+		}
+	}
+
 	dma_addr = dma_map_single_attrs(ctx->jrdev, ctx->sh_desc_update,
 					offsetof(struct caam_hash_ctx, key),
 					ctx->dir, DMA_ATTR_SKIP_CPU_SYNC);
 	if (dma_mapping_error(ctx->jrdev, dma_addr)) {
 		dev_err(ctx->jrdev, "unable to map shared descriptors\n");
 
-		if (is_xcbc_aes(caam_hash->alg_type))
+		if (ctx->key_dir != DMA_NONE)
 			dma_unmap_single_attrs(ctx->jrdev, ctx->adata.key_dma,
 					       ARRAY_SIZE(ctx->key),
-					       DMA_BIDIRECTIONAL,
+					       ctx->key_dir,
 					       DMA_ATTR_SKIP_CPU_SYNC);
 
 		caam_jr_free(ctx->jrdev);
@@ -1891,9 +1914,9 @@  static void caam_hash_cra_exit(struct crypto_tfm *tfm)
 	dma_unmap_single_attrs(ctx->jrdev, ctx->sh_desc_update_dma,
 			       offsetof(struct caam_hash_ctx, key),
 			       ctx->dir, DMA_ATTR_SKIP_CPU_SYNC);
-	if (is_xcbc_aes(ctx->adata.algtype))
+	if (ctx->key_dir != DMA_NONE)
 		dma_unmap_single_attrs(ctx->jrdev, ctx->adata.key_dma,
-				       ARRAY_SIZE(ctx->key), DMA_BIDIRECTIONAL,
+				       ARRAY_SIZE(ctx->key), ctx->key_dir,
 				       DMA_ATTR_SKIP_CPU_SYNC);
 	caam_jr_free(ctx->jrdev);
 }
diff --git a/drivers/crypto/caam/desc_constr.h b/drivers/crypto/caam/desc_constr.h
index 8154174..536f360 100644
--- a/drivers/crypto/caam/desc_constr.h
+++ b/drivers/crypto/caam/desc_constr.h
@@ -533,14 +533,26 @@  static inline void append_proto_dkp(u32 * const desc, struct alginfo *adata)
 	if (adata->key_inline) {
 		int words;
 
-		append_operation(desc, OP_TYPE_UNI_PROTOCOL | protid |
-				 OP_PCL_DKP_SRC_IMM | OP_PCL_DKP_DST_IMM |
-				 adata->keylen);
-		append_data(desc, adata->key_virt, adata->keylen);
+		if (adata->keylen > adata->keylen_pad) {
+			append_operation(desc, OP_TYPE_UNI_PROTOCOL | protid |
+					 OP_PCL_DKP_SRC_PTR |
+					 OP_PCL_DKP_DST_IMM | adata->keylen);
+			append_ptr(desc, adata->key_dma);
+
+			words = (ALIGN(adata->keylen_pad, CAAM_CMD_SZ) -
+				 CAAM_PTR_SZ) / CAAM_CMD_SZ;
+		} else {
+			append_operation(desc, OP_TYPE_UNI_PROTOCOL | protid |
+					 OP_PCL_DKP_SRC_IMM |
+					 OP_PCL_DKP_DST_IMM | adata->keylen);
+			append_data(desc, adata->key_virt, adata->keylen);
+
+			words = (ALIGN(adata->keylen_pad, CAAM_CMD_SZ) -
+				 ALIGN(adata->keylen, CAAM_CMD_SZ)) /
+				CAAM_CMD_SZ;
+		}
 
 		/* Reserve space in descriptor buffer for the derived key */
-		words = (ALIGN(adata->keylen_pad, CAAM_CMD_SZ) -
-			 ALIGN(adata->keylen, CAAM_CMD_SZ)) / CAAM_CMD_SZ;
 		if (words)
 			(*desc) = cpu_to_caam32(caam32_to_cpu(*desc) + words);
 	} else {
diff --git a/drivers/crypto/caam/key_gen.c b/drivers/crypto/caam/key_gen.c
index c6f8375..5a851dd 100644
--- a/drivers/crypto/caam/key_gen.c
+++ b/drivers/crypto/caam/key_gen.c
@@ -48,18 +48,20 @@  int gen_split_key(struct device *jrdev, u8 *key_out,
 	u32 *desc;
 	struct split_key_result result;
 	dma_addr_t dma_addr;
+	unsigned int local_max;
 	int ret = -ENOMEM;
 
 	adata->keylen = split_key_len(adata->algtype & OP_ALG_ALGSEL_MASK);
 	adata->keylen_pad = split_key_pad_len(adata->algtype &
 					      OP_ALG_ALGSEL_MASK);
+	local_max = max(keylen, adata->keylen_pad);
 
 	dev_dbg(jrdev, "split keylen %d split keylen padded %d\n",
 		adata->keylen, adata->keylen_pad);
 	print_hex_dump_debug("ctx.key@" __stringify(__LINE__)": ",
 			     DUMP_PREFIX_ADDRESS, 16, 4, key_in, keylen, 1);
 
-	if (adata->keylen_pad > max_keylen)
+	if (local_max > max_keylen)
 		return -EINVAL;
 
 	desc = kmalloc(CAAM_CMD_SZ * 6 + CAAM_PTR_SZ * 2, GFP_KERNEL | GFP_DMA);
@@ -70,8 +72,7 @@  int gen_split_key(struct device *jrdev, u8 *key_out,
 
 	memcpy(key_out, key_in, keylen);
 
-	dma_addr = dma_map_single(jrdev, key_out, adata->keylen_pad,
-				  DMA_BIDIRECTIONAL);
+	dma_addr = dma_map_single(jrdev, key_out, local_max, DMA_BIDIRECTIONAL);
 	if (dma_mapping_error(jrdev, dma_addr)) {
 		dev_err(jrdev, "unable to map key memory\n");
 		goto out_free;
@@ -117,7 +118,7 @@  int gen_split_key(struct device *jrdev, u8 *key_out,
 				     adata->keylen_pad, 1);
 	}
 
-	dma_unmap_single(jrdev, dma_addr, adata->keylen_pad, DMA_BIDIRECTIONAL);
+	dma_unmap_single(jrdev, dma_addr, local_max, DMA_BIDIRECTIONAL);
 out_free:
 	kfree(desc);
 	return ret;