CVE-2025-38733

Summary

In the Linux kernel, the following vulnerability has been resolved:

s390/mm: Do not map lowcore with identity mapping

Since the identity mapping is pinned to address zero the lowcore is always also mapped to address zero, this happens regardless of the relocate_lowcore command line option. If the option is specified the lowcore is mapped twice, instead of only once.

This means that NULL pointer accesses will succeed instead of causing an exception (low address protection still applies, but covers only parts). To fix this never map the first two pages of physical memory with the identity mapping.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux32db401965f165f7c44447d0508097f070c8f576 < 30bf5728bb217a6d1ba73f44094c9b9c6bc9a567affected
LinuxLinux32db401965f165f7c44447d0508097f070c8f576 < 1d7864acd497cb468a998d44631f84896f885e85affected
LinuxLinux32db401965f165f7c44447d0508097f070c8f576 < 93f616ff870a1fb7e84d472cad0af651b18f9f87affected
LinuxLinux0b99d0e17d6a73a0526f92bc6b54b2b95e67a31daffected
LinuxLinux6.10.11 < 6.11affected
LinuxLinux6.11affected
LinuxLinux0 < 6.11unaffected
LinuxLinux6.12.44 <= 6.12.*unaffected
LinuxLinux6.16.4 <= 6.16.*unaffected
LinuxLinux6.17 <= *unaffected

Weaknesses

References