Out-of-Bounds Access Vulnerability in Linux Kernel Affecting Memory Management

CVE-2025-40008

What is CVE-2025-40008?

A vulnerability has been identified in the Linux kernel relating to improper memory handling during SHA-224 Kunit testing. The issue arises when a buffer is not 4-byte aligned and reaches the end of a guard page, leading to a crash due to out-of-bounds access in shadow memory. Specifically, the kmsan_internal_set_shadow_origin function accesses incorrect shadow bytes, utilizing unrounded shadow addresses which can read beyond allocated memory. This incorrect memory access can cause system instability and crashes. A fix has been implemented to ensure proper alignment of shadow addresses before memory access.

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