CVE-2021-46990

Summary

CVE-2021-46990 is a vulnerability affecting the Linux kernel on PowerPC/64 architectures. The issue involves crashes when toggling entry flush mitigation, which can be enabled or disabled at runtime through a debugfs file. However, the patching required for this operation may not be safe if other CPUs are active, potentially resulting in a corrupted LR (Link Register) that points to the kernel. This issue has been resolved by performing the patching under a stopped machine, ensuring that only the CPU doing the patching is active. This approach minimizes the risk of potential crashes or security vulnerabilities.

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