[BUGFIX] dm-crypt: Fix a bug of async cryption complete function

[Huang Ying]

In async cryption complete function (kcryptd_async_done), the
crypto_async_request passed in may be different from the one passed to
crypto_ablkcipher_encrypt/decrypt. Only crypto_async_request->data is
guaranteed to be same as the passed in one. Current kcryptd_async_done
uses passed in crypto_async_request directly, which may cause AES-NI
based AES algorithm implementation panic.

This patch fix this bug by using crypto_async_request->data only,
which point to dm_crypt_request, the crypto_async_request passed in
and original data (convert_context) can be gotten from
dm_crypt_request.

Signed-off-by: Huang Ying <ying.huang@xxxxxxxxx>

---
 drivers/md/dm-crypt.c |   14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -60,6 +60,8 @@ struct dm_crypt_io {
 };
 
 struct dm_crypt_request {
+	struct ablkcipher_request *req;
+	struct convert_context *ctx;
 	struct scatterlist sg_in;
 	struct scatterlist sg_out;
 };
@@ -349,6 +351,8 @@ static int crypt_convert_block(struct cr
 	iv = (u8 *)ALIGN((unsigned long)(dmreq + 1),
 			 crypto_ablkcipher_alignmask(cc->tfm) + 1);
 
+	dmreq->req = req;
+	dmreq->ctx = ctx;
 	sg_init_table(&dmreq->sg_in, 1);
 	sg_set_page(&dmreq->sg_in, bv_in->bv_page, 1 << SECTOR_SHIFT,
 		    bv_in->bv_offset + ctx->offset_in);
@@ -391,12 +395,15 @@ static void kcryptd_async_done(struct cr
 static void crypt_alloc_req(struct crypt_config *cc,
 			    struct convert_context *ctx)
 {
+	struct dm_crypt_request *dmreq;
+
 	if (!cc->req)
 		cc->req = mempool_alloc(cc->req_pool, GFP_NOIO);
 	ablkcipher_request_set_tfm(cc->req, cc->tfm);
+	dmreq = (struct dm_crypt_request *)((char *)cc->req + cc->dmreq_start);
 	ablkcipher_request_set_callback(cc->req, CRYPTO_TFM_REQ_MAY_BACKLOG |
 					     CRYPTO_TFM_REQ_MAY_SLEEP,
-					     kcryptd_async_done, ctx);
+					     kcryptd_async_done, dmreq);
 }
 
 /*
@@ -821,7 +828,8 @@ static void kcryptd_crypt_read_convert(s
 static void kcryptd_async_done(struct crypto_async_request *async_req,
 			       int error)
 {
-	struct convert_context *ctx = async_req->data;
+	struct dm_crypt_request *dmreq = async_req->data;
+	struct convert_context *ctx = dmreq->ctx;
 	struct dm_crypt_io *io = container_of(ctx, struct dm_crypt_io, ctx);
 	struct crypt_config *cc = io->target->private;
 
@@ -830,7 +838,7 @@ static void kcryptd_async_done(struct cr
 		return;
 	}
 
-	mempool_free(ablkcipher_request_cast(async_req), cc->req_pool);
+	mempool_free(dmreq->req, cc->req_pool);
 
 	if (!atomic_dec_and_test(&ctx->pending))
 		return;

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