Re: [PATCH v3] siphash: add cryptographically secure hashtable function

From: Jason A. Donenfeld
Date: Tue Dec 13 2016 - 17:46:56 EST

Hi Eric,

On Tue, Dec 13, 2016 at 9:39 AM, Eric Biggers <ebiggers3@xxxxxxxxx> wrote:
> Hmm, I don't think you can really do load_unaligned_zeropad() without first
> checking for 'left != 0'. The fixup section for load_unaligned_zeropad()
> assumes that rounding the pointer down to a word boundary will produce an
> address from which an 'unsigned long' can be loaded. But if 'left = 0' and we
> happen to be on a page boundary with the next page unmapped, then this will not
> be true and the second load will still fault.

Excellent point. I haven't been able to trigger this in my
experiments, but it doesn't look like there's much to prevent this
from happening. I'll submit a v4 with this as fixed, since there
hasn't been any other code quality issues.