[PATCH] crypto: vmx - CTR: always increment IV as quadword

[Daniel Axtens <dja@axtens.net>]

The kernel self-tests picked up an issue with CTR mode:
alg: skcipher: p8_aes_ctr encryption test failed (wrong result) on test vector 3, cfg="uneven misaligned splits, may sleep"

Test vector 3 has an IV of FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFD, so
after 3 increments it should wrap around to 0.

In the aesp8-ppc code from OpenSSL, 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. It is a pretty narrow edge case: I am really
impressed by the quality of the kernel self-tests!

Fixes: 5c380d623ed3 ("crypto: vmx - Add support for VMS instructions by ASM")
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Axtens <dja@axtens.net>

---

I'll pass this along internally to get it into OpenSSL as well.
---
 drivers/crypto/vmx/aesp8-ppc.pl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/crypto/vmx/aesp8-ppc.pl b/drivers/crypto/vmx/aesp8-ppc.pl
index de78282b8f44..9c6b5c1d6a1a 100644
--- a/drivers/crypto/vmx/aesp8-ppc.pl
+++ b/drivers/crypto/vmx/aesp8-ppc.pl
@@ -1357,7 +1357,7 @@ 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
-- 
2.19.1