Date: Thu, 15 Mar 2018 11:42:25 +0100 From: Salvatore Mesoraca <s.mesoraca16@...il.com> To: Herbert Xu <herbert@...dor.apana.org.au> Cc: linux-kernel@...r.kernel.org, Kernel Hardening <kernel-hardening@...ts.openwall.com>, linux-crypto@...r.kernel.org, "David S. Miller" <davem@...emloft.net>, Kees Cook <keescook@...omium.org> Subject: Re: [PATCH] crypto: ctr: avoid VLA use 2018-03-15 10:54 GMT+01:00 Herbert Xu <herbert@...dor.apana.org.au>: > 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 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
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