CVE-2021-47429

CVE-2021-47429: vulnerability in Linux

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

Published · Updated

3Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackepss 0.2%
exploitation probability
0.2%top 92% of all CVEs
observed exploitation
nono source reports it
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.
Affected products
Linux · Linux