Linux Kernel Vulnerability in TASK_SIZE_MAX Handling by Vendor

CVE-2025-38434

What is CVE-2025-38434?

A critical issue was identified in the Linux kernel related to the improper handling of TASK_SIZE_MAX, which could potentially allow invalid memory addresses to be accepted during user space operations. The flaw was due to the assumption that all user addresses are less than LONG_MAX, but certain cases, particularly with get_user_pages_fast(), did not enforce this correctly. As a result, memory accesses in the range between TASK_SIZE and LONG_MAX could bypass validation checks, leading to potential exploitation. This vulnerability has been addressed by reverting changes to ensure TASK_SIZE_MAX aligns with the default TASK_SIZE, trading off some performance for improved security.

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