CVE-2025-38733

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> s390/mm: Do not map lowcore with identity mapping<br /> <br /> Since the identity mapping is pinned to address zero the lowcore is always<br /> also mapped to address zero, this happens regardless of the relocate_lowcore<br /> command line option. If the option is specified the lowcore is mapped<br /> twice, instead of only once.<br /> <br /> This means that NULL pointer accesses will succeed instead of causing an<br /> exception (low address protection still applies, but covers only parts).<br /> To fix this never map the first two pages of physical memory with the<br /> identity mapping.