Red Hat: CVE-2024-50115: kernel: KVM: nSVM: Ignore nCR3[4:0] when loading PDPTEs from memory (Multiple Advisories)

Red Hat: CVE-2024-50115: kernel: KVM: nSVM: Ignore nCR3[4:0] when loading PDPTEs from memory (Multiple Advisories)

Severity

4

CVSS

(AV:L/AC:H/Au:S/C:C/I:N/A:N)

Published

11/05/2024

Created

02/11/2025

Added

02/10/2025

Modified

02/10/2025

Description

In the Linux kernel, the following vulnerability has been resolved: KVM: nSVM: Ignore nCR3[4:0] when loading PDPTEs from memory Ignore nCR3[4:0] when loading PDPTEs from memory for nested SVM, as bits 4:0 of CR3 are ignored when PAE paging is used, and thus VMRUN doesn't enforce 32-byte alignment of nCR3. In the absolute worst case scenario, failure to ignore bits 4:0 can result in an out-of-bounds read, e.g. if the target page is at the end of a memslot, and the VMM isn't using guard pages. Per the APM: The CR3 register points to the base address of the page-directory-pointer table. The page-directory-pointer table is aligned on a 32-byte boundary, with the low 5 address bits 4:0 assumed to be 0. And the SDM's much more explicit: 4:0Ignored Note, KVM gets this right when loading PDPTRs, it's only the nSVM flow that is broken.

Solution(s)

• redhat-upgrade-kernel
• redhat-upgrade-kernel-rt

References

• CVE-2024-50115
• RHSA-2024:11486