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

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Date:   Wed, 14 Jul 2021 21:40:28 +0200
From:   Pavel Machek <pavel@...x.de>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Thara Gopinath <thara.gopinath@...aro.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Sasha Levin <sashal@...nel.org>
Subject: 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.

> index a2d3da0ad95f..5a6559131eac 100644
> --- a/drivers/crypto/qce/skcipher.c
> +++ b/drivers/crypto/qce/skcipher.c
> @@ -122,21 +122,22 @@ qce_skcipher_async_req_handle(struct crypto_async_request *async_req)
>  	sg_mark_end(sg);
>  	rctx->dst_sg = rctx->dst_tbl.sgl;

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 <weiyongjun1@...wei.com>
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 <hulkci@...wei.com>
	    Signed-off-by: Wei Yongjun <weiyongjun1@...wei.com>
	    

Best regards,
								Pavel
-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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