[PATCH v2] crypto: sun4i-ss - Remove insecure and unused rng_alg

[Herbert Xu]

On Mon, Jun 01, 2026 at 04:07:57PM +0000, Eric Biggers wrote:
> Remove sun4i_ss_rng, as it is insecure and unused:
> 
> - It has multiple vulnerabilities.  sun4i_ss_prng_seed() is missing
>   locking and has a buffer overflow.  sun4i_ss_prng_generate() fails to
>   fill the entire buffer with cryptographic random bytes, because it
>   rounds the destination length down and also doesn't actually wait for
>   the hardware to be ready before pulling bytes from it.
> 
> - No user of this code is known.  It's usable only theoretically via the
>   "rng" algorithm type of AF_ALG.  But userspace actually just uses the
>   actual Linux RNG (/dev/random etc) instead.  And rng_algs don't
>   contribute entropy to the actual Linux RNG either.  (This may have
>   been confused with hwrng, which does contribute entropy.)
> 
> The sun4i_ss_prng_seed() buffer overflow was reported by Tianchu Chen
> and discovered by Atuin - Automated Vulnerability Discovery Engine
> 
> There's no point in fixing all these vulnerabilities individually when
> this is unused code, so let's just remove it.
> 
> Fixes: b8ae5c7387ad ("crypto: sun4i-ss - support the Security System PRNG")
> Cc: stable at vger.kernel.org
> Reported-by: Tianchu Chen <flynnnchen at tencent.com>
> Closes: https://lore.kernel.org/r/af749a8447bd7f0e9dd26ca6c87e9c6afecb09d9@linux.dev/
> Acked-by: Corentin LABBE <clabbe.montjoie at gmail.com>
> Signed-off-by: Eric Biggers <ebiggers at kernel.org>
> ---
> 
> This patch is targeting crypto/master
> 
> v2: rebased onto crypto/master, and added Acked-by and Reported-by
> 
>  arch/arm/configs/sunxi_defconfig              |  1 -
>  drivers/crypto/allwinner/Kconfig              |  8 ---
>  drivers/crypto/allwinner/sun4i-ss/Makefile    |  1 -
>  .../crypto/allwinner/sun4i-ss/sun4i-ss-core.c | 36 ----------
>  .../crypto/allwinner/sun4i-ss/sun4i-ss-prng.c | 69 -------------------
>  drivers/crypto/allwinner/sun4i-ss/sun4i-ss.h  | 20 ------
>  6 files changed, 135 deletions(-)
>  delete mode 100644 drivers/crypto/allwinner/sun4i-ss/sun4i-ss-prng.c

Patch applied.  Thanks.
-- 
Email: Herbert Xu <herbert at gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt