Re: [PATCH] crypto: sun8i-ce: fix memory leak and return value of sun8i_ce_hash_run

On Mon, Jul 26, 2021 at 2:48 PM Corentin Labbe
[off-list ref] wrote:

Le Mon, Jul 26, 2021 at 02:27:50PM +0800, Dongliang Mu a écrit :

quoted

This patch fixes some memory leak caused by dma_mmap_sg/single
in the error handling code. In addition, it fixes the return value
when errors related with dma_mmap_sg/single occur.

Reported-by: Dongliang Mu <redacted>
Fixes: 732b764099f65 ("crypto: sun8i-ce - fix two error path's memory leak")
Signed-off-by: Dongliang Mu <redacted>
---
 .../crypto/allwinner/sun8i-ss/sun8i-ss-hash.c | 37 ++++++++++---------
 1 file changed, 20 insertions(+), 17 deletions(-)

diff --git a/drivers/crypto/allwinner/sun8i-ss/sun8i-ss-hash.c b/drivers/crypto/allwinner/sun8i-ss/sun8i-ss-hash.c
index 3c073eb3db03..7c4ed19f5466 100644
--- a/drivers/crypto/allwinner/sun8i-ss/sun8i-ss-hash.c
+++ b/drivers/crypto/allwinner/sun8i-ss/sun8i-ss-hash.c

@@ -324,11 +324,11 @@ int sun8i_ss_hash_run(struct crypto_engine *engine, void *breq)
      struct sun8i_ss_alg_template *algt;
      struct sun8i_ss_dev *ss;
      struct scatterlist *sg;
-     int nr_sgs, err, digestsize;
+     int j, i, todo, nr_sgs, tmp_err, digestsize;
+     int err = 0;
      unsigned int len;
      u64 fill, min_fill, byte_count;
      void *pad, *result;
-     int j, i, todo;
      __be64 *bebits;
      __le64 *lebits;
      dma_addr_t addr_res, addr_pad;

@@ -368,14 +368,14 @@ int sun8i_ss_hash_run(struct crypto_engine *engine, void *breq)
      if (nr_sgs <= 0 || nr_sgs > MAX_SG) {
              dev_err(ss->dev, "Invalid sg number %d\n", nr_sgs);
              err = -EINVAL;
-             goto theend;
+             goto err_result;
      }

      addr_res = dma_map_single(ss->dev, result, digestsize, DMA_FROM_DEVICE);
      if (dma_mapping_error(ss->dev, addr_res)) {
              dev_err(ss->dev, "DMA map dest\n");
              err = -EINVAL;
-             goto theend;
+             goto err_unmap_sg;
      }

      len = areq->nbytes;

@@ -390,7 +390,7 @@ int sun8i_ss_hash_run(struct crypto_engine *engine, void *breq)
      if (len > 0) {
              dev_err(ss->dev, "remaining len %d\n", len);
              err = -EINVAL;
-             goto theend;
+             goto err_addr_res;
      }

      byte_count = areq->nbytes;

@@ -421,27 +421,30 @@ int sun8i_ss_hash_run(struct crypto_engine *engine, void *breq)
      }

      addr_pad = dma_map_single(ss->dev, pad, j * 4, DMA_TO_DEVICE);
-     rctx->t_src[i].addr = addr_pad;
-     rctx->t_src[i].len = j;
-     rctx->t_dst[i].addr = addr_res;
-     rctx->t_dst[i].len = digestsize / 4;
      if (dma_mapping_error(ss->dev, addr_pad)) {
              dev_err(ss->dev, "DMA error on padding SG\n");
              err = -EINVAL;
-             goto theend;
+             goto err_addr_res;
      }
+     rctx->t_src[i].addr = addr_pad;
+     rctx->t_src[i].len = j;
+     rctx->t_dst[i].addr = addr_res;
+     rctx->t_dst[i].len = digestsize / 4;

-     err = sun8i_ss_run_hash_task(ss, rctx, crypto_tfm_alg_name(areq->base.tfm));
+     tmp_err = sun8i_ss_run_hash_task(ss, rctx, crypto_tfm_alg_name(areq->base.tfm));
+
+     memcpy(areq->result, result, algt->alg.hash.halg.digestsize);
+
+     crypto_finalize_hash_request(engine, breq, tmp_err);

      dma_unmap_single(ss->dev, addr_pad, j * 4, DMA_TO_DEVICE);
+err_addr_res:
+     dma_unmap_single(ss->dev, addr_res, digestsize, DMA_FROM_DEVICE);
+err_unmap_sg:
      dma_unmap_sg(ss->dev, areq->src, sg_nents(areq->src),
                   DMA_TO_DEVICE);
-     dma_unmap_single(ss->dev, addr_res, digestsize, DMA_FROM_DEVICE);
-
-     memcpy(areq->result, result, algt->alg.hash.halg.digestsize);
-theend:
+err_result:
      kfree(pad);
      kfree(result);
-     crypto_finalize_hash_request(engine, breq, err);
-     return 0;
+     return err;
 }

Hello

This is wrong, you need to always call crypto_finalize_hash_request()

Do you have tested your changes ? Copying results before dma_unmap() is also very wrong, this will lead to random cache fail.

I am sorry I don't test my changes due to no PoC or input at hand. If
you know any PoC for me to test, please let me know. Thanks in
advance.

I am not familiar with this code. All my intention is to fix the leak
caused by the incorrect error handling code.

Your reply indicated two pieces of information:

1. crypto_finalize_hash_request must be executed and placed at the end
2. memcpy must be executed after dma_unmap_*() functions.

Any other information I missed? I can address those issues and send a v2 patch.

Regards

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