CVE-2021-46997

Summary

CVE-2021-46997 is a vulnerability affecting the Linux kernel on arm64 architecture. During kernel entry, a inconsistency exists between the interrupt status indicated by the PMR and the actual interrupt masking state, leading to a warning message from lockdep. This occurs due to the manipulation of the PMR during exception entry, which can indicate interrupts are unmasked even when they are masked by DAIF. To resolve this issue, the PMR must be consistently set during exception entry and local_daif_inherit() updated accordingly. The warning message can be removed by setting (GIC_PRIO_IRQON | GIC_PRIO_PSR_I_SET) for consistency with local_daif_save(). This vulnerability was discovered during kernel entry with the command line argument "irqchip.gicv3_pseudo_nmi=1".

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