ppc assembly pack: always increment CTR IV as quadword
authorDaniel Axtens <dja@axtens.net>
Fri, 17 May 2019 00:59:40 +0000 (10:59 +1000)
committerDaniel Axtens <dja@axtens.net>
Fri, 17 May 2019 01:05:16 +0000 (11:05 +1000)
The kernel self-tests picked up an issue with CTR mode. The issue was
detected with a test vector with an IV of
FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFD: after 3 increments it should wrap
around to 0.

There are two paths that increment IVs: the bulk (8 at a time) path,
and the individual path which is used when there are fewer than 8 AES
blocks to process.

In the bulk path, the IV is incremented with vadduqm: "Vector Add
Unsigned Quadword Modulo", which does 128-bit addition.

In the individual path, however, the IV is incremented with vadduwm:
"Vector Add Unsigned Word Modulo", which instead does 4 32-bit
additions. Thus the IV would instead become
FFFFFFFFFFFFFFFFFFFFFFFF00000000, throwing off the result.

Use vadduqm.

This was probably a typo originally, what with q and w being
adjacent.

CLA: trivial

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/8942)

crypto/aes/asm/aesp8-ppc.pl

index 44056e3..30ccecf 100755 (executable)
@@ -1331,7 +1331,7 @@ Loop_ctr32_enc:
        addi            $idx,$idx,16
        bdnz            Loop_ctr32_enc
 
-       vadduwm         $ivec,$ivec,$one
+       vadduqm         $ivec,$ivec,$one
         vmr            $dat,$inptail
         lvx            $inptail,0,$inp
         addi           $inp,$inp,16