CVE-2026-80835: crypto: qcom-rng - Remove crypto_rng interface

CVE-2026-80835: crypto: qcom-rng - Remove crypto_rng interface

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

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

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

crypto: qcom-rng - Remove crypto_rng interface

qcom-rng.c exposes the same hardware through two completely separate
interfaces, crypto_rng and hwrng.  However, the implementation of this
is buggy because it permits generation operations from these interfaces
to run concurrently with each other, accessing the same registers.  That
is, qcom_rng_generate() synchronizes with itself but not with
qcom_hwrng_read().  This results in potential repetition of output from
the RNG, output of non-random values, etc.

Fortunately, there's actually no point in hardware RNG drivers
implementing the crypto_rng interface.  It's not actually used by
anything besides the "rng" algorithm type of AF_ALG, which in turn is
not actually used in practice.  Other crypto_rng hardware drivers are
likewise being phased out, leaving just the hwrng support.

Thus, remove it to simplify the code and avoid conflict (and confusion)
with the hwrng interface which is the one that actually matters.

The Linux kernel CVE team has assigned CVE-2026-80835 to this issue.


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

	Issue introduced in 6.7 with commit f29cd5bb64c258f29b4c49452532481f50eb43ca and fixed in 6.12.108 with commit bb474dcd9d0224264a27a60891f00872b879835f
	Issue introduced in 6.7 with commit f29cd5bb64c258f29b4c49452532481f50eb43ca and fixed in 6.18.49 with commit 14d9ee8286460a7b82f3b8610b5c7ebf4550b06b
	Issue introduced in 6.7 with commit f29cd5bb64c258f29b4c49452532481f50eb43ca and fixed in 7.1.13 with commit 843e2bdaf8deb8bc341203094dfe582e38ea4af2
	Issue introduced in 6.7 with commit f29cd5bb64c258f29b4c49452532481f50eb43ca and fixed in 7.2.3 with commit 669d940351eda316b82e24986e2e0e057653ce7d
	Issue introduced in 6.7 with commit f29cd5bb64c258f29b4c49452532481f50eb43ca and fixed in 7.3-rc1 with commit 2ecdf5c9910e20f73639bc322f0518a3439d17c0

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-2026-80835
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:
	drivers/crypto/Kconfig
	drivers/crypto/qcom-rng.c


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/bb474dcd9d0224264a27a60891f00872b879835f
	https://git.kernel.org/stable/c/14d9ee8286460a7b82f3b8610b5c7ebf4550b06b
	https://git.kernel.org/stable/c/843e2bdaf8deb8bc341203094dfe582e38ea4af2
	https://git.kernel.org/stable/c/669d940351eda316b82e24986e2e0e057653ce7d
	https://git.kernel.org/stable/c/2ecdf5c9910e20f73639bc322f0518a3439d17c0