crypto: caam/qi2 - fix zero-length buffer DMA mapping

Commit 04e6d25c5bb2 ("crypto: caam - fix zero-length buffer DMA mapping")
fixed an issue in caam/jr driver where ahash implementation was
DMA mapping a zero-length buffer.

Current commit applies a similar fix for caam/qi2 driver.

Cc: <stable@vger.kernel.org> # v4.20+
Fixes: 3f16f6c9d632 ("crypto: caam/qi2 - add support for ahash algorithms")
Signed-off-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 18 insertions, 7 deletions

diff --git a/drivers/crypto/caam/caamalg_qi2.c b/drivers/crypto/caam/caamalg_qi2.c
index d19c97acf1aa..f3aac3efd51c 100644
--- a/drivers/crypto/caam/caamalg_qi2.c
+++ b/drivers/crypto/caam/caamalg_qi2.c
@@ -3795,10 +3795,13 @@ static int ahash_final_no_ctx(struct ahash_request *req)
         if (!edesc)
                 return ret;
 
-        state->buf_dma = dma_map_single(ctx->dev, buf, buflen, DMA_TO_DEVICE);
-        if (dma_mapping_error(ctx->dev, state->buf_dma)) {
-                dev_err(ctx->dev, "unable to map src\n");
-                goto unmap;
+        if (buflen) {
+                state->buf_dma = dma_map_single(ctx->dev, buf, buflen,
+                                                DMA_TO_DEVICE);
+                if (dma_mapping_error(ctx->dev, state->buf_dma)) {
+                        dev_err(ctx->dev, "unable to map src\n");
+                        goto unmap;
+                }
         }
 
         edesc->dst_dma = dma_map_single(ctx->dev, req->result, digestsize,
@@ -3811,9 +3814,17 @@ static int ahash_final_no_ctx(struct ahash_request *req)
 
         memset(&req_ctx->fd_flt, 0, sizeof(req_ctx->fd_flt));
         dpaa2_fl_set_final(in_fle, true);
-        dpaa2_fl_set_format(in_fle, dpaa2_fl_single);
-        dpaa2_fl_set_addr(in_fle, state->buf_dma);
-        dpaa2_fl_set_len(in_fle, buflen);
+        /*
+         * crypto engine requires the input entry to be present when
+         * "frame list" FD is used.
+         * Since engine does not support FMT=2'b11 (unused entry type), leaving
+         * in_fle zeroized (except for "Final" flag) is the best option.
+         */
+        if (buflen) {
+                dpaa2_fl_set_format(in_fle, dpaa2_fl_single);
+                dpaa2_fl_set_addr(in_fle, state->buf_dma);
+                dpaa2_fl_set_len(in_fle, buflen);
+        }
         dpaa2_fl_set_format(out_fle, dpaa2_fl_single);
         dpaa2_fl_set_addr(out_fle, edesc->dst_dma);
         dpaa2_fl_set_len(out_fle, digestsize);