linux-kernel - [PATCH 5.1 010/405] crypto: vmx - CTR: always increment IV as quadword

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Message-Id: <20190530030540.936691473@linuxfoundation.org>
Date:   Wed, 29 May 2019 20:00:08 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Daniel Axtens <dja@...ens.net>,
        Nayna Jain <nayna@...ux.ibm.com>,
        Herbert Xu <herbert@...dor.apana.org.au>
Subject: [PATCH 5.1 010/405] crypto: vmx - CTR: always increment IV as quadword

From: Daniel Axtens <dja@...ens.net>

commit 009b30ac7444c17fae34c4f435ebce8e8e2b3250 upstream.

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@...r.kernel.org
Signed-off-by: Daniel Axtens <dja@...ens.net>
Acked-by: Nayna Jain <nayna@...ux.ibm.com>
Tested-by: Nayna Jain <nayna@...ux.ibm.com>
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/crypto/vmx/aesp8-ppc.pl |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- 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