Linux Kernel Memory Management Vulnerability in Process Operations

CVE-2025-39992

What is CVE-2025-39992?

A memory management flaw in the Linux kernel occurs during process fork operations and swapoff processes, which can lead to kernel NULL pointer dereference errors. This vulnerability arises from a race condition where the memory address space is not fully initialized before use, specifically when a process is being duplicated and a swapoff operation occurs concurrently. When this happens, the system may attempt to access a zero entry as if it were a valid virtual memory area, causing a crash. Developers must ensure that partially valid memory trees are not exposed during operations to prevent such failures, and the introduction of checks like MMF_UNSTABLE is critical in mitigating this issue.

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