powercap: intel_rapl: Fix a NULL pointer dereference

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: powercap: intel_rapl: Fix a NULL pointer dereference A NULL pointer dereference is triggered when probing the MMIO RAPL driver on platforms with CPU ID not listed in intel_rapl_common CPU model list. This is because the intel_rapl_common module still probes on such platforms even if 'defaults_msr' is not set after commit 1488ac990ac8 ("powercap: intel_rapl: Allow probing without CPUID match"). Thus the MMIO RAPL rp->priv->defaults is NULL when registering to RAPL framework. Fix the problem by adding sanity check to ensure rp->priv->rapl_defaults is always valid.

References

• https://git.kernel.org/stable/c/0641908b906a133f1494c312a71f9fecbe2b6c78
• https://git.kernel.org/stable/c/9b254feb249981b66ccdb1dae54e757789a15ba1
• https://git.kernel.org/stable/c/2f73cf2ae5e0f4e629db5be3a4380ff7807148e6
• https://git.kernel.org/stable/c/2d1f5006ff95770da502f8cee2a224a1ff83866e