[PATCH 3/4] crypto: qce: Ensure QCE receives no zero-sized updates

[Iaroslav Gridin]

From: Voker57 <voke...@gmail.com>

Zero-sized updates lock QCE, so ensure there's always some data left
for the final update, up to blocksize.
Signed-off-by: Iaroslav Gridin <voke...@gmail.com>
---
 drivers/crypto/qce/sha.c | 30 ++++++++++++++++++++----------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/drivers/crypto/qce/sha.c b/drivers/crypto/qce/sha.c
index a068d39..f199f28 100644
--- a/drivers/crypto/qce/sha.c
+++ b/drivers/crypto/qce/sha.c
@@ -240,9 +240,11 @@ static int qce_ahash_update(struct ahash_request *req)
        struct qce_device *qce = tmpl->qce;
        struct scatterlist *sg_last, *sg;
        unsigned int total, len;
+       unsigned int tmpbuflen = 0;
        unsigned int hash_later;
        unsigned int nbytes;
        unsigned int blocksize;
+       unsigned int src_offset;
 
        blocksize = crypto_tfm_alg_blocksize(crypto_ahash_tfm(tfm));
        rctx->count += req->nbytes;
@@ -265,21 +267,30 @@ static int qce_ahash_update(struct ahash_request *req)
         * if we have data from previous update copy them on buffer. The old
         * data will be combined with current request bytes.
         */
-       if (rctx->buflen)
+       if (rctx->buflen) {
                memcpy(rctx->tmpbuf, rctx->buf, rctx->buflen);
+               tmpbuflen = rctx->buflen;
+       }
 
        /* calculate how many bytes will be hashed later */
        hash_later = total % blocksize;
-       if (hash_later) {
-               unsigned int src_offset = req->nbytes - hash_later;
-               scatterwalk_map_and_copy(rctx->buf, req->src, src_offset,
-                                        hash_later, 0);
-       }
+       /* ensure we always have something on buffer */
+       if (hash_later == 0)
+               hash_later = blocksize;
+       src_offset = req->nbytes - hash_later;
+       scatterwalk_map_and_copy(rctx->buf, req->src, src_offset,
+                                hash_later, 0);
+       rctx->buflen = hash_later;
 
        /* here nbytes is multiple of blocksize */
        nbytes = total - hash_later;
 
-       len = rctx->buflen;
+       len = tmpbuflen;
+
+       /* Zero-length update is a no-op */
+       if (nbytes == 0)
+               return 0;
+
        sg = sg_last = req->src;
 
        while (len < nbytes && sg) {
@@ -293,15 +304,14 @@ static int qce_ahash_update(struct ahash_request *req)
 
        sg_mark_end(sg_last);
 
-       if (rctx->buflen) {
+       if (tmpbuflen) {
                sg_init_table(rctx->sg, 2);
-               sg_set_buf(rctx->sg, rctx->tmpbuf, rctx->buflen);
+               sg_set_buf(rctx->sg, rctx->tmpbuf, tmpbuflen);
                sg_chain(rctx->sg, 2, req->src);
                req->src = rctx->sg;
        }
 
        req->nbytes = nbytes;
-       rctx->buflen = hash_later;
 
        return qce->async_req_enqueue(tmpl->qce, &req->base);
 }
-- 
2.9.3

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