linux-kernel - Re: [PATCH v3] crypto: talitos - fix ablkcipher for CONFIG_VMAP

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Date:   Fri, 4 Jan 2019 15:17:25 +0000
From:   Horia Geanta <horia.geanta@....com>
To:     Christophe Leroy <christophe.leroy@....fr>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>
CC:     "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>
Subject: Re: [PATCH v3] crypto: talitos - fix ablkcipher for CONFIG_VMAP_STACK

On 12/21/2018 10:07 AM, Christophe Leroy wrote:
[snip]
> IV cannot be on stack when CONFIG_VMAP_STACK is selected because the stack
> cannot be DMA mapped anymore.
> This looks better, thanks.

> This patch copies the IV into the extended descriptor when iv is not
> a valid linear address.
> 
Though I am not sure the checks in place are enough.

> Fixes: 4de9d0b547b9 ("crypto: talitos - Add ablkcipher algorithms")
> Cc: stable@...r.kernel.org
> Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
> ---
>  v3: Using struct edesc buffer.
> 
>  v2: Using per-request context.
[snip]
> +	if (ivsize && !virt_addr_valid(iv))
> +		alloc_len += ivsize;
[snip]
>  
> +	if (ivsize && !virt_addr_valid(iv))
A more precise condition would be (!is_vmalloc_addr || is_vmalloc_addr(iv))

It matches the checks in debug_dma_map_single() helper, though I am not sure
they are enough to rule out all exceptions of DMA API.

> +		iv = memcpy(((u8 *)edesc) + alloc_len - ivsize, iv, ivsize);
> +
>  	edesc->src_nents = src_nents;
>  	edesc->dst_nents = dst_nents;
> -	edesc->iv_dma = iv_dma;
> +	if (ivsize)
> +		edesc->iv_dma = dma_map_single(dev, iv, ivsize, DMA_TO_DEVICE);
> +	else
> +		edesc->iv_dma = 0;
> +