Re: [PATCH v3] crypto: talitos - fix ablkcipher for CONFIG_VMAP_STACK

[Horia Geanta]

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@xxxxxxxxxxxxxxx
> Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
> ---
>  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;
> +