CVE-2021-47429

powerpc/64s: Fix unrecoverable MCE calling async handler from NMI

Description

In the Linux kernel, the following vulnerability has been resolved: powerpc/64s: Fix unrecoverable MCE calling async handler from NMI The machine check handler is not considered NMI on 64s. The early handler is the true NMI handler, and then it schedules the machine_check_exception handler to run when interrupts are enabled. This works fine except the case of an unrecoverable MCE, where the true NMI is taken when MSR[RI] is clear, it can not recover, so it calls machine_check_exception directly so something might be done about it. Calling an async handler from NMI context can result in irq state and other things getting corrupted. This can also trigger the BUG at arch/powerpc/include/asm/interrupt.h:168 BUG_ON(!arch_irq_disabled_regs(regs) && !(regs->msr & MSR_EE)); Fix this by making an _async version of the handler which is called in the normal case, and a NMI version that is called for unrecoverable interrupts.

N/A

CVSS

Severity:

EPSS 0.08%

Affected: Linux Linux

References

Link	Tags
https://git.kernel.org/stable/c/d7a8e38999fbd6910516e44cb43f9f4317e54f73
https://git.kernel.org/stable/c/f08fb25bc66986b0952724530a640d9970fa52c1

Frequently Asked Questions

What is the severity of CVE-2021-47429?: CVE-2021-47429 has not yet been assigned a CVSS score.
How to fix CVE-2021-47429?: To fix CVE-2021-47429, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-47429 being actively exploited in the wild?: As for now, there are no information to confirm that CVE-2021-47429 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-47429?: CVE-2021-47429 affects Linux Linux, Linux Linux.

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