1 files changed, 94 insertions, 53 deletions

diff --git a/crypto/ahash.c b/crypto/ahash.c
index a92dc382f781..6e7223392e80 100644
--- a/crypto/ahash.c
+++ b/crypto/ahash.c
@@ -190,6 +190,75 @@ static inline unsigned int ahash_align_buffer_size(unsigned len,
         return len + (mask & ~(crypto_tfm_ctx_alignment() - 1));
 }
 
+static int ahash_save_req(struct ahash_request *req, crypto_completion_t cplt)
+{
+        struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
+        unsigned long alignmask = crypto_ahash_alignmask(tfm);
+        unsigned int ds = crypto_ahash_digestsize(tfm);
+        struct ahash_request_priv *priv;
+
+        priv = kmalloc(sizeof(*priv) + ahash_align_buffer_size(ds, alignmask),
+                       (req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP) ?
+                       GFP_KERNEL : GFP_ATOMIC);
+        if (!priv)
+                return -ENOMEM;
+
+        /*
+         * WARNING: Voodoo programming below!
+         *
+         * The code below is obscure and hard to understand, thus explanation
+         * is necessary. See include/crypto/hash.h and include/linux/crypto.h
+         * to understand the layout of structures used here!
+         *
+         * The code here will replace portions of the ORIGINAL request with
+         * pointers to new code and buffers so the hashing operation can store
+         * the result in aligned buffer. We will call the modified request
+         * an ADJUSTED request.
+         *
+         * The newly mangled request will look as such:
+         *
+         * req {
+         *   .result        = ADJUSTED[new aligned buffer]
+         *   .base.complete = ADJUSTED[pointer to completion function]
+         *   .base.data     = ADJUSTED[*req (pointer to self)]
+         *   .priv          = ADJUSTED[new priv] {
+         *           .result   = ORIGINAL(result)
+         *           .complete = ORIGINAL(base.complete)
+         *           .data     = ORIGINAL(base.data)
+         *   }
+         */
+
+        priv->result = req->result;
+        priv->complete = req->base.complete;
+        priv->data = req->base.data;
+        /*
+         * WARNING: We do not backup req->priv here! The req->priv
+         *          is for internal use of the Crypto API and the
+         *          user must _NOT_ _EVER_ depend on it's content!
+         */
+
+        req->result = PTR_ALIGN((u8 *)priv->ubuf, alignmask + 1);
+        req->base.complete = cplt;
+        req->base.data = req;
+        req->priv = priv;
+
+        return 0;
+}
+
+static void ahash_restore_req(struct ahash_request *req)
+{
+        struct ahash_request_priv *priv = req->priv;
+
+        /* Restore the original crypto request. */
+        req->result = priv->result;
+        req->base.complete = priv->complete;
+        req->base.data = priv->data;
+        req->priv = NULL;
+
+        /* Free the req->priv.priv from the ADJUSTED request. */
+        kzfree(priv);
+}
+
 static void ahash_op_unaligned_finish(struct ahash_request *req, int err)
 {
         struct ahash_request_priv *priv = req->priv;
@@ -201,47 +270,37 @@ static void ahash_op_unaligned_finish(struct ahash_request *req, int err)
                 memcpy(priv->result, req->result,
                        crypto_ahash_digestsize(crypto_ahash_reqtfm(req)));
 
-        kzfree(priv);
+        ahash_restore_req(req);
 }
 
 static void ahash_op_unaligned_done(struct crypto_async_request *req, int err)
 {
         struct ahash_request *areq = req->data;
-        struct ahash_request_priv *priv = areq->priv;
-        crypto_completion_t complete = priv->complete;
-        void *data = priv->data;
 
-        ahash_op_unaligned_finish(areq, err);
+        /*
+         * Restore the original request, see ahash_op_unaligned() for what
+         * goes where.
+         *
+         * The "struct ahash_request *req" here is in fact the "req.base"
+         * from the ADJUSTED request from ahash_op_unaligned(), thus as it
+         * is a pointer to self, it is also the ADJUSTED "req" .
+         */
 
-        areq->base.complete = complete;
-        areq->base.data = data;
+        /* First copy req->result into req->priv.result */
+        ahash_op_unaligned_finish(areq, err);
 
-        complete(&areq->base, err);
+        /* Complete the ORIGINAL request. */
+        areq->base.complete(&areq->base, err);
 }
 
 static int ahash_op_unaligned(struct ahash_request *req,
                               int (*op)(struct ahash_request *))
 {
-        struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
-        unsigned long alignmask = crypto_ahash_alignmask(tfm);
-        unsigned int ds = crypto_ahash_digestsize(tfm);
-        struct ahash_request_priv *priv;
         int err;
 
-        priv = kmalloc(sizeof(*priv) + ahash_align_buffer_size(ds, alignmask),
-                       (req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP) ?
-                       GFP_KERNEL : GFP_ATOMIC);
-        if (!priv)
-                return -ENOMEM;
-
-        priv->result = req->result;
-        priv->complete = req->base.complete;
-        priv->data = req->base.data;
-
-        req->result = PTR_ALIGN((u8 *)priv->ubuf, alignmask + 1);
-        req->base.complete = ahash_op_unaligned_done;
-        req->base.data = req;
-        req->priv = priv;
+        err = ahash_save_req(req, ahash_op_unaligned_done);
+        if (err)
+                return err;
 
         err = op(req);
         ahash_op_unaligned_finish(req, err);
@@ -290,19 +349,16 @@ static void ahash_def_finup_finish2(struct ahash_request *req, int err)
                 memcpy(priv->result, req->result,
                        crypto_ahash_digestsize(crypto_ahash_reqtfm(req)));
 
-        kzfree(priv);
+        ahash_restore_req(req);
 }
 
 static void ahash_def_finup_done2(struct crypto_async_request *req, int err)
 {
         struct ahash_request *areq = req->data;
-        struct ahash_request_priv *priv = areq->priv;
-        crypto_completion_t complete = priv->complete;
-        void *data = priv->data;
 
         ahash_def_finup_finish2(areq, err);
 
-        complete(data, err);
+        areq->base.complete(&areq->base, err);
 }
 
 static int ahash_def_finup_finish1(struct ahash_request *req, int err)
@@ -322,38 +378,23 @@ out:
 static void ahash_def_finup_done1(struct crypto_async_request *req, int err)
 {
         struct ahash_request *areq = req->data;
-        struct ahash_request_priv *priv = areq->priv;
-        crypto_completion_t complete = priv->complete;
-        void *data = priv->data;
 
         err = ahash_def_finup_finish1(areq, err);
 
-        complete(data, err);
+        areq->base.complete(&areq->base, err);
 }
 
 static int ahash_def_finup(struct ahash_request *req)
 {
         struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
-        unsigned long alignmask = crypto_ahash_alignmask(tfm);
-        unsigned int ds = crypto_ahash_digestsize(tfm);
-        struct ahash_request_priv *priv;
-
-        priv = kmalloc(sizeof(*priv) + ahash_align_buffer_size(ds, alignmask),
-                       (req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP) ?
-                       GFP_KERNEL : GFP_ATOMIC);
-        if (!priv)
-                return -ENOMEM;
-
-        priv->result = req->result;
-        priv->complete = req->base.complete;
-        priv->data = req->base.data;
+        int err;
 
-        req->result = PTR_ALIGN((u8 *)priv->ubuf, alignmask + 1);
-        req->base.complete = ahash_def_finup_done1;
-        req->base.data = req;
-        req->priv = priv;
+        err = ahash_save_req(req, ahash_def_finup_done1);
+        if (err)
+                return err;
 
-        return ahash_def_finup_finish1(req, tfm->update(req));
+        err = tfm->update(req);
+        return ahash_def_finup_finish1(req, err);
 }
 
 static int ahash_no_export(struct ahash_request *req, void *out)