Re: [PATCH] crypto: ctr: avoid VLA use

[Salvatore Mesoraca]

2018-03-15 10:54 GMT+01:00 Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>:
> On Wed, Mar 14, 2018 at 02:17:30PM +0100, Salvatore Mesoraca wrote:
>> All ciphers implemented in Linux have a block size less than or
>> equal to 16 bytes and the most demanding hw require 16 bits
>> alignment for the block buffer.
>> We avoid 2 VLAs[1] by always allocating 16 bytes with 16 bits
>> alignment, unless the architecture support efficient unaligned
>> accesses.
>> We also check, at runtime, that our assumptions still stand,
>> possibly dynamically allocating a new buffer, just in case
>> something changes in the future.
>
> Please move the check to ctr instance creation time.  That is,
> if the underlying blocksize is greater than 16 bytes than simply
> fail the creation.

Good, I'll send a v2.
Thank you for your help,

Salvatore