Bug 2373557 (CVE-2022-50232)

Summary: CVE-2022-50232 kernel: arm64: set UXN on swapper page tables
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
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Hardware: All   
OS: Linux   
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Description OSIDB Bzimport 2025-06-18 12:08:13 UTC
In the Linux kernel, the following vulnerability has been resolved:

arm64: set UXN on swapper page tables

[ This issue was fixed upstream by accident in c3cee924bd85 ("arm64:
  head: cover entire kernel image in initial ID map") as part of a
  large refactoring of the arm64 boot flow. This simple fix is therefore
  preferred for -stable backporting ]

On a system that implements FEAT_EPAN, read/write access to the idmap
is denied because UXN is not set on the swapper PTEs. As a result,
idmap_kpti_install_ng_mappings panics the kernel when accessing
__idmap_kpti_flag. Fix it by setting UXN on these PTEs.

Comment 1 Avinash Hanwate 2025-06-19 12:49:15 UTC
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025061851-CVE-2022-50232-373d@gregkh/T