Bug 2298129 (CVE-2022-48793)

Summary: CVE-2022-48793 kernel: KVM: x86: nSVM: fix potential NULL derefernce on nested migration
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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Fixed In Version: kernel 5.15.25, kernel 5.16.11, kernel 5.17 Doc Type: If docs needed, set a value
Doc Text:
A vulnerability was found in the nested.c file in the Linux kernel's KVM driver, where a potential NULL dereference can occur. This happens when the call to load the nested state is executed before Nested Page Tables (NPT) are enabled, preventing access to guest memory, lead to system instability and a denial of service during nested migration processes.
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Description OSIDB Bzimport 2024-07-16 12:26:32 UTC 
In the Linux kernel, the following vulnerability has been resolved:

KVM: x86: nSVM: fix potential NULL derefernce on nested migration

Turns out that due to review feedback and/or rebases
I accidentally moved the call to nested_svm_load_cr3 to be too early,
before the NPT is enabled, which is very wrong to do.

KVM can't even access guest memory at that point as nested NPT
is needed for that, and of course it won't initialize the walk_mmu,
which is main issue the patch was addressing.

Fix this for real.
Comment 7 errata-xmlrpc 2024-08-21 11:52:55 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
  Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions
  Red Hat Enterprise Linux 8.6 Telecommunications Update Service

Via RHSA-2024:5692 https://access.redhat.com/errata/RHSA-2024:5692