Re: [PATCH 5.10 129/593] crypto: qce: skcipher: Fix incorrect sg count for dma transfers

Hi!

[ Upstream commit 1339a7c3ba05137a2d2fe75f602311bbfc6fab33 ]

Use the sg count returned by dma_map_sg to call into
dmaengine_prep_slave_sg rather than using the original sg count. dma_map_sg
can merge consecutive sglist entries, thus making the original sg count
wrong. This is a fix for memory coruption issues observed while testing
encryption/decryption of large messages using libkcapi framework.

Patch has been tested further by running full suite of tcrypt.ko tests
including fuzz tests.

This still needs more work AFAICT.

ret is == 0 at this point.

-	ret = dma_map_sg(qce->dev, rctx->dst_sg, rctx->dst_nents, dir_dst);
-	if (ret < 0)
+	dst_nents = dma_map_sg(qce->dev, rctx->dst_sg, rctx->dst_nents, dir_dst);
+	if (dst_nents < 0)
 		goto error_free;

And we go to the error path, and return ret... instead of returning failure.

 	if (diff_dst) {
-		ret = dma_map_sg(qce->dev, req->src, rctx->src_nents, dir_src);
-		if (ret < 0)
+		src_nents = dma_map_sg(qce->dev, req->src, rctx->src_nents, dir_src);
+		if (src_nents < 0)
 			goto error_unmap_dst;
 		rctx->src_sg = req->src;

Same problem happens here.

The problem is already fixed in the mainline; I believe we want that
in 5.10-stable at least.

commit a8bc4f5e7a72e4067f5afd7e98b61624231713ca
Author: Wei Yongjun [off-list ref]
Date:   Wed Jun 2 11:36:45 2021 +0000

    crypto: qce - fix error return code in qce_skcipher_async_req_handle()

    Fix to return a negative error code from the error handling
        case instead of 0, as done elsewhere in this function.

    Fixes: 1339a7c3ba05 ("crypto: qce: skcipher: Fix incorrect sg
    count for dma transfers")
        Reported-by: Hulk Robot [off-list ref]
	    Signed-off-by: Wei Yongjun [off-list ref]
	    

Best regards,
								Pavel
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