CVE-2026-64307: crypto: ccp - Do not initialize SNP for ioctl(SNP_CONFIG)

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

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

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

crypto: ccp - Do not initialize SNP for ioctl(SNP_CONFIG)

Sashiko notes:

> if SEV initialization fails and KVM is actively running normal VMs, could a
> userspace process trigger this code path via /dev/sev ioctls (e.g.,
> SEV_PDH_GEN) and zero out MSR_VM_HSAVE_PA globally? Would the next VMRUN
> execution for an active VM trigger a general protection fault and crash the
> host?

Refuse to re-try initialization if SNP is not already initialized for
SNP_CONFIG.

This is technically an ABI break: before if SNP initialization failed it
could be transparently retriggered by this ioctl, and if no VMs were
running, everything worked fine. Hopefully this is enough of a corner case
that nobody will notice, but someone does, there are a few options:

* do something like symbol_get() for kvm and refuse to initialize if KVM is
  loaded
* check each cpu's HSAVE_PA for non-zero data before re-initializing
* once initialization has failed, continue to refuse to initialize until
  the ccp module is unloaded

The Linux kernel CVE team has assigned CVE-2026-64307 to this issue.


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

	Issue introduced in 6.12.75 with commit 1c3506ea8599a3ad1b9aae5cbd573134f8d18db7 and fixed in 6.12.97 with commit 345a6e869b33687e9268044bcaeeefd7c61da675
	Issue introduced in 6.16 with commit ceac7fb89e8da465aec3ac3c20477f912f5c3a6c and fixed in 6.18.39 with commit 441ea32cf2755a0dc593557056b00b7caa0651f5
	Issue introduced in 6.16 with commit ceac7fb89e8da465aec3ac3c20477f912f5c3a6c and fixed in 7.1.4 with commit 20f548cdac94860a164e5ebba4f7e4a01051cb06
	Issue introduced in 6.16 with commit ceac7fb89e8da465aec3ac3c20477f912f5c3a6c and fixed in 7.2-rc1 with commit 08f0e65e784c4b20e6e620dd4f68d8636073a3d2

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-2026-64307
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/ccp/sev-dev.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/345a6e869b33687e9268044bcaeeefd7c61da675
	https://git.kernel.org/stable/c/441ea32cf2755a0dc593557056b00b7caa0651f5
	https://git.kernel.org/stable/c/20f548cdac94860a164e5ebba4f7e4a01051cb06
	https://git.kernel.org/stable/c/08f0e65e784c4b20e6e620dd4f68d8636073a3d2