CVE-2026-52969 — KVM: Reject wrapped offset in kvm_reset_dirty_gfn()

2026-10-18T01:18:07.008859+00:00

Affected: Linux, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9

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

KVM: Reject wrapped offset in kvm_reset_dirty_gfn()

kvm_reset_dirty_gfn() guards the gfn range with

if (!memslot || (offset + __fls(mask)) >= memslot->npages) return;

but offset is u64 and the addition is unchecked. The check can be silently bypassed by a u64 wrap.

The dirty ring backing those entries is MAP_SHARED at KVM_DIRTY_LOG_PAGE_OFFSET of the vcpu fd, so the VMM can rewrite the slot and offset fields of any entry between when the kernel pushes them and when KVM_RESET_DIRTY_RINGS consumes them. On reset, kvm_dirty_ring_reset() re-reads the values via READ_ONCE() and feeds them straight back into this check; only the flags handshake is treated as the handover, the slot/offset payload is taken on trust.

Crafting two entries

entry[i].offset = 0xffffffffffffffc1 entry[i+1].offset = 0

makes the coalescing loop in kvm_dirty_ring_reset() compute

delta = (s64)(0 - 0xffffffffffffffc1) = 63

which falls in [0, BITS_PER_LONG), so it folds entry[i+1] into the existing mask by setting bit 63. The trailing kvm_reset_dirty_gfn() call then sees offset = 0xffffffffffffffc1 and __fls(mask) = 63; the sum is 0 in u64 and the bounds check passes.

That offset propagates into kvm_arch_mmu_enable_log_dirty_pt_masked() unchanged. On the legacy MMU path -- kvm_memslots_have_rmaps() == true, i.e. shadow paging, any VM that has allocated shadow roots, or a write-tracked slot -- it reaches gfn_to_rmap(), whi…

USN-8566-1 — linux, linux-gcp, linux-gke, linux-realtime vulnerabilities

2026-10-18T01:18:07.009051+00:00

Affected: Ubuntu:26.04:LTS: linux, Ubuntu:26.04:LTS: linux-gcp, Ubuntu:26.04:LTS: linux-gke, Ubuntu:26.04:LTS: linux-realtime

It was discovered that some AMD Zen 2 processors did not properly isolate shared resources in the operation cache. A local attacker could possibly use this issue to corrupt instructions executed at a higher privilege level, resulting in privilege escalation. (CVE-2025-54518)

Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems: - PSP security protocol; - ARM64 architecture; - PowerPC architecture; - RISC-V architecture; - S390 architecture; - User-Mode Linux (UML); - x86 architecture; - Block layer subsystem; - Cryptographic API; - Intel NPU Driver; - DRBD Distributed Replicated Block Device drivers; - Ublk userspace block driver; - Bluetooth drivers; - Bus devices; - Character device driver; - Clock framework and drivers; - CPU frequency scaling framework; - Hardware crypto device drivers; - EDAC drivers; - EFI core; - FWCTL subsystem; - GPU drivers; - HID subsystem; - I3C subsystem; - InfiniBand drivers; - IOMMU subsystem; - Mailbox framework; - Multiple devices driver; - Media drivers; - NVIDIA Tegra memory controller driver; - MTD block device drivers; - Network drivers; - Ethernet bonding driver; - Mellanox network drivers; - Microsoft Azure Network Adapter (MANA) driver; - STMicroelectronics network drivers; - MediaTek network drivers; - NVME drivers; - PCI subsystem;…

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CVE-2026-52969 — KVM: Reject wrapped offset in kvm_reset_dirty_gfn()

USN-8566-1 — linux, linux-gcp, linux-gke, linux-realtime vulnerabilities