CVE-2026-74438: crypto: sun4i-ss - Remove insecure and unused rng_alg

From: Greg Kroah-Hartman <[email protected]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

crypto: sun4i-ss - Remove insecure and unused rng_alg

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.

The Linux kernel CVE team has assigned CVE-2026-74438 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 4.14 with commit b8ae5c7387ad075ee61e8c8774ce2bca46bc9236 and fixed in 5.15.212 with commit 2eafecaba1b46bb9774eaf3556619fd5b6a17c1c
	Issue introduced in 4.14 with commit b8ae5c7387ad075ee61e8c8774ce2bca46bc9236 and fixed in 6.1.178 with commit ee2458f8188732aa53a5d42f56e87bfad288b44e
	Issue introduced in 4.14 with commit b8ae5c7387ad075ee61e8c8774ce2bca46bc9236 and fixed in 6.6.145 with commit 306ded31bfa00a69d25823a60d7c797170bfb4f8
	Issue introduced in 4.14 with commit b8ae5c7387ad075ee61e8c8774ce2bca46bc9236 and fixed in 6.12.97 with commit e4b7b9819811c4c51064c3d3d3c02f0be7491707
	Issue introduced in 4.14 with commit b8ae5c7387ad075ee61e8c8774ce2bca46bc9236 and fixed in 6.18.40 with commit c401492e01c7bfd38cf14c94d85c7efafe7d1a25
	Issue introduced in 4.14 with commit b8ae5c7387ad075ee61e8c8774ce2bca46bc9236 and fixed in 7.1.5 with commit 9c8086d9511189c34dfa3f9e3a03f2bee12f56a5
	Issue introduced in 4.14 with commit b8ae5c7387ad075ee61e8c8774ce2bca46bc9236 and fixed in 7.2-rc1 with commit b2c41fa9dd8fc740c489e060b199165771f268d1

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-74438
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	arch/arm/configs/sunxi_defconfig
	drivers/crypto/allwinner/Kconfig
	drivers/crypto/allwinner/sun4i-ss/Makefile
	drivers/crypto/allwinner/sun4i-ss/sun4i-ss-core.c
	drivers/crypto/allwinner/sun4i-ss/sun4i-ss-prng.c
	drivers/crypto/allwinner/sun4i-ss/sun4i-ss.h


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/2eafecaba1b46bb9774eaf3556619fd5b6a17c1c
	https://git.kernel.org/stable/c/ee2458f8188732aa53a5d42f56e87bfad288b44e
	https://git.kernel.org/stable/c/306ded31bfa00a69d25823a60d7c797170bfb4f8
	https://git.kernel.org/stable/c/e4b7b9819811c4c51064c3d3d3c02f0be7491707
	https://git.kernel.org/stable/c/c401492e01c7bfd38cf14c94d85c7efafe7d1a25
	https://git.kernel.org/stable/c/9c8086d9511189c34dfa3f9e3a03f2bee12f56a5
	https://git.kernel.org/stable/c/b2c41fa9dd8fc740c489e060b199165771f268d1