Commit 009b30ac authored by Daniel Axtens's avatar Daniel Axtens Committed by Herbert Xu

crypto: vmx - CTR: always increment IV as quadword

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: 5c380d62 ("crypto: vmx - Add support for VMS instructions by ASM")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarDaniel Axtens <dja@axtens.net>
Acked-by: default avatarNayna Jain <nayna@linux.ibm.com>
Tested-by: default avatarNayna Jain <nayna@linux.ibm.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent e1354400
......@@ -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
......
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