Bug 2492289 (CVE-2026-52968)

Summary: CVE-2026-52968 kernel: KVM: s390: pci: fix GAIT table indexing due to double-scaling pointer arithmetic
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's KVM (Kernel-based Virtual Machine) subsystem, specifically affecting s390 PCI devices. This vulnerability arises from incorrect pointer arithmetic during the indexing of the Guest Access Instruction Table (GAIT), leading to out-of-bounds memory access. A local attacker or a malicious guest operating system could exploit this to read or write data beyond allocated memory boundaries, potentially causing system instability or a denial of service.
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Description OSIDB Bzimport 2026-06-24 18:03:32 UTC 
In the Linux kernel, the following vulnerability has been resolved:

KVM: s390: pci: fix GAIT table indexing due to double-scaling pointer arithmetic

kvm_s390_pci_aif_enable(), kvm_s390_pci_aif_disable(), and
aen_host_forward() index the GAIT by manually multiplying the index
with sizeof(struct zpci_gaite).

Since aift->gait is already a struct zpci_gaite pointer, this
double-scales the offset, accessing element aisb*16 instead of aisb.

This causes out-of-bounds accesses when aisb >= 32 (with
ZPCI_NR_DEVICES=512)

Fix by removing the erroneous sizeof multiplication.
Comment 1 Mauro Matteo Cascella 2026-06-25 15:35:15 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062438-CVE-2026-52968-8803@gregkh/T