[PATCH 4.4 080/241] crypto: vmx - CTR: always increment IV as quadword

From: Greg Kroah-Hartman
Date: Sun Jun 09 2019 - 13:03:38 EST

From: Daniel Axtens <dja@xxxxxxxxxx>

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"

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

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@xxxxxxxxxxxxxxx
Signed-off-by: Daniel Axtens <dja@xxxxxxxxxx>
Acked-by: Nayna Jain <nayna@xxxxxxxxxxxxx>
Tested-by: Nayna Jain <nayna@xxxxxxxxxxxxx>
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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
@@ -1298,7 +1298,7 @@ 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