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: sta...@vger.kernel.org
Signed-off-by: Daniel Axtens <d...@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
