Don't assume alignment of ChaCha key on ARM.

When addressing [1], I checked the AEAD code but brain-farted: a key is
aligned in that code, but it's the Poly1305 key, which doesn't matter
here.

It would be nice to align the ChaCha key too, but Android doesn't have
|posix_memalign| in the versions that we care about. It does have
|memalign|, but that's documented as "obsolete" and we don't have a
concept of an Android OS yet and I don't want to add one just for this.

So this change uses the buffer for loading the key again.

(Note that we never used to check for alignment of the |key| before
calling this. We must have gotten it for free somehow when checking the
alignment of |in| and |out|. But there are clearly some paths that don't
have an aligned key:
https://code.google.com/p/chromium/issues/detail?id=454308.)

At least the generation script started paying off immediately ☺.

[1] https://boringssl-review.googlesource.com/#/c/3132/1/crypto/chacha/chacha_vec.c@185

Change-Id: I4f893ba0733440fddd453f9636cc2aeaf05076ed
Reviewed-on: https://boringssl-review.googlesource.com/3270
Reviewed-by: Adam Langley <agl@google.com>
2 files changed