CVE-2026-98433

What the bug is

In kvmppc_svm_page_in(), if uv_page_in() fails after kvmppc_uvmem_get_page() has succeeded, the secure device page is never released. kvmppc_uvmem_get_page() sets a bit in kvmppc_uvmem_bitmap, allocates a kvmppc_uvmem_page_pvt struct, marks the GFN as KVMPPC_GFN_UVMEM_PFN, and calls zone_device_page_init() which sets refcount=1 and locks the page. The subsequent goto out_finalize skips the *mig.dst assignment, so migrate_vma_finalize() is a no-op for the page, and none of those resources are ever reclaimed. Each occurrence permanently consumes one entry from the firmware-bounded secure memory pool (kvmppc_uvmem_bitmap), leaks pvt, and leaves the GFN marked as secure — making it unusable for the lifetime of the VM. The twin __kvmppc_svm_page_out() already handles the analogous uv_page_out() failure correctly with unlock_page(dpage); __free_page(dpage). Apply the same pattern here: unlock_page() followed by put_page(), which chains through free_zone_device_folio() into kvmppc_uvmem_folio_free() to clear the bitmap bit, free pvt, and reset the GFN state. Reachable whenever uv_page_in() returns an error (e.g. UV pool exhaustion) on any POWER9/10 + Ultravisor/PEF system.

Where it lives

The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.

arch/powerpc/kvm/book3s_hv_uvmem.c

What this is

KERNEL VIRTUAL MACHINE FOR POWERPC (KVM/powerpc)MAINTAINERS section matched on arch/powerpc/kvm/ · linuxppc-dev@lists.ozlabs.org · Maintained (Book3S 64-bit HV)

Kernel module

none to look for. The file would have gone into kvm_hv, and Debian does not compile it into that module, so finding kvm_hv in lsmod would say nothing about this CVE.

Check it on the machine

grep -wE 'CONFIG_KVM|CONFIG_KVM_BOOK3S_64_HV|CONFIG_PPC_UV' /boot/config-$(uname -r)

Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.

Show whether Debian builds this, per release

Debian does not build this code. In 4 releases below, every kernel flavour Debian publishes has the switch off, so the vulnerable file is compiled into no kernel binary Debian ships.

• bookworm, trixie, forky, sidn

n

not enabled on any flavour - this release does not build the code

Build switches

CONFIG_KVM, CONFIG_KVM_BOOK3S_64_HV, CONFIG_PPC_UV

Reads as

all on means the file is compiled; any one off means it is not.

From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages

Signals

Published

2026-10-18 (today)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

not scored

CISA KEV

not listedthe KEV catalogue

Debian urgency

not yet assignedsource

Subsystem

arch/powerpc

Upstream fixes

The versions the CNA records as introducing and fixing this, and the commit for each. source

Introduced	Fixed in	Commit
5.5	5.10.271	ed2f2ff63cb7
5.5	5.15.222	8f3b7746874b
5.5	6.1.189	a933d7024359
5.5	6.6.158	c41088b2765a
5.5	6.12.112	f3d4b2fc30c9
5.5	6.18.54	dfb842749327
5.5	7.2.8	fcbff8008b0e
5.5	7.3	0a416ee20bcc