Re: [PATCH] lib/crypto: mips: Disable Octeon SHA code on little-endian kernels

["Ard Biesheuvel" <ardb@kernel.org>]

On Thu, 22 Oct 2026, at 07:44, Eric Biggers wrote:
> Kernels built for the MIPS64-based Cavium Octeon SoCs are normally
> big-endian, but little-endian builds are also supported.  Currently, the
> SHA-1, SHA-256, and SHA-512 code using the Octeon crypto co-processor is
> enabled in both builds.
>
> This code is untestable without the hardware.  However, based on the
> code itself, it is implausible that it computes hash values correctly in
> little-endian builds.  Such builds write many incorrect values to COP2:
>
>   - SHA-1 and SHA-256: The 64-bit integer that contains the last two
>     32-bit message words of each block is written to COP2 entirely
>     byte-reflected, due to missing endianness conversion in
>     octeon_sha1_start() and octeon_sha256_start() to compensate for
>     using native 64-bit loads from the message bytes.  This differs from
>     all the earlier message words which are written correctly.
>
>     Furthermore, the state is written to COP2 with each 32-bit word
>     byte-reflected within each 64-bit integer, due to incorrect use of
>     64-bit endianness conversion in write_octeon_64bit_hash_dword() when
>     the state is kept in memory in native-endian 32-bit words.
>
>   - SHA-512: All the 64-bit message words are written to COP2
>     byte-reflected, due to missing endianness conversion in
>     write_octeon_64bit_block_sha512() and octeon_sha512_start().  The
>     SHA-512 state words seem to be written correctly.
>
> Big-endian kernels aren't affected by these bugs.  These bugs also
> aren't new; this code has been broken on little-endian ever since it and
> Octeon little-endian support were first added in v4.1.
>
> Commit d2a948d2db68 ("MIPS: Octeon: Make octeon-md5 driver
> endian-agnostic") made the MD5 code work on little-endian kernels by
> adding 64-bit endianness conversions to the COP2 macros used by MD5
> (some of which are shared by SHA-1 and SHA-256, despite those algorithms
> keeping the state words in native-endian instead of MD5's little-endian,
> causing some of the strange behavior described above).  However, SHA-1,
> SHA-256, and SHA-512 were never fixed to work on little-endian kernels.
>
> Therefore, disable the Octeon SHA-1, SHA-256, and SHA-512 code in
> little-endian kernels.  This causes the generic code that actually
> computes hash values correctly to be used instead.
>
> Fixes: 82be2dcfa6a1 ("crypto: octeon - add SHA1 module")
> Fixes: c3d0def62001 ("crypto: octeon - add SHA256 module")
> Fixes: fbaa4dfd51a0 ("crypto: octeon - add SHA512 module")
> Cc: stable@vger.kernel.org
> Signed-off-by: Eric Biggers <ebiggers@kernel.org>
> ---

Acked-by: Ard Biesheuvel <ardb@kernel.org>