BUG: p8_aes_ctr randomly returns wrong results

Ondrej Mosnáček omosnacek at gmail.com
Wed Mar 13 23:48:55 AEDT 2019

st 13. 3. 2019 o 13:37 Ondrej Mosnáček <omosnacek at gmail.com> napísal(a):
> Hi,
> FYI, the p8_aes_ctr crypto driver (drivers/crypto/vmx/aes_ctr.c) seems
> to be seriously broken. When I do repeated encryption using libkcapi
> multiple times in a row, I sometimes get a wrong result. This happens
> more often with long messages (e.g. at 16 KiB it already happens very
> frequently).
> To reproduce:
> 1. Install or locally build libkcapi [1] (you will need the kcapi-enc
> binary in PATH) on a ppc64le system.
> 2. Run the following in bash:
> for i in {1..100}; do head -c $((16*1024)) /dev/zero | kcapi-enc -e -c
> 'ctr(aes)' -p test -s test --pbkdfiter 1 2>/dev/null | sha256sum; done
> | sort -u
> Expected result:
> All invocations produce output with identical checksum.
> Actual result:
> Multiple different checksums are produced.
> When I run 'rmmod vmx_crypto' before running the reproducer, I get
> only one (correct) checksum, so this is definitely a bug in the
> driver. Other ciphers (cbc(aes), xts(aes)) are not affected, even
> though the glue code is very similar. That leads me to believe the
> problem is somewhere in the assembly code.
> [1] http://github.com/smuellerDD/libkcapi
> Cheers,
> Ondrej

(Ah, forgot to compare email addresses with MAINTAINERS... let me try these)

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