CVE-2024-50115

Summary

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:

4:0 Ignored

Note, KVM gets this right when loading PDPTRs, it's only the nSVM flow that is broken.

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxe4e517b4be019787ada4cbbce2f04570c21b0cbd < 76ce386feb14ec9a460784fcd495d8432acce7a5affected
LinuxLinuxe4e517b4be019787ada4cbbce2f04570c21b0cbd < 58cb697d80e669c56197f703e188867c8c54c494affected
LinuxLinuxe4e517b4be019787ada4cbbce2f04570c21b0cbd < 6876793907cbe19d42e9edc8c3315a21e06c32aeaffected
LinuxLinuxe4e517b4be019787ada4cbbce2f04570c21b0cbd < 2c4adc9b192a0815fe58a62bc0709449416cc884affected
LinuxLinuxe4e517b4be019787ada4cbbce2f04570c21b0cbd < 426682afec71ea3f889b972d038238807b9443e4affected
LinuxLinuxe4e517b4be019787ada4cbbce2f04570c21b0cbd < f559b2e9c5c5308850544ab59396b7d53cfc67bdaffected
LinuxLinux3.2affected
LinuxLinux0 < 3.2unaffected
LinuxLinux5.10.229 <= 5.10.*unaffected
LinuxLinux5.15.170 <= 5.15.*unaffected
LinuxLinux6.1.115 <= 6.1.*unaffected
LinuxLinux6.6.59 <= 6.6.*unaffected
LinuxLinux6.11.6 <= 6.11.*unaffected
LinuxLinux6.12 <= *unaffected

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

CVE Program Container

Additional References

References