cve 2025 38135

CVE-2025-38135 is a Linux kernel vulnerability involving a missing NULL check in the mlb_usio_probe function of a serial driver. The bug can cause a null pointer dereference, potentially leading to a denial-of-service crash on affected systems. The fix adds a check for the return value of devm_ioremap() to handle NULL returns properly. This issue highlights how routine memory-mapping calls and subtle API semantics remain common sources of kernel instability and security impact. While the vulnerability is low-level, it underscores the importance of careful error handling in kernel code.