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

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Date:   Mon, 7 Jan 2019 18:06:15 +0100
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Horia Geanta <horia.geanta@....com>,
        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



Le 04/01/2019 à 16:24, Horia Geanta a écrit :
> On 1/4/2019 5:17 PM, Horia Geanta wrote:
>> 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))
>>
> Sorry for the typo, I meant:
> (!virt_addr_valid(iv) || is_vmalloc_addr(iv))

As far as I know, virt_addr_valid() means the address is in the linear 
memory space. So it cannot be a vmalloc_addr if it is a linear space 
addr, can it ?

At least, it is that way on powerpc which is the arch embedding the 
talitos crypto engine. virt_addr_valid() means we are under max_pfn, 
while VMALLOC_START is above max_pfn.

Christophe

> 
>> 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.