cxl/ras: Fix CPER handler device confusion

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: cxl/ras: Fix CPER handler device confusion By inspection, cxl_cper_handle_prot_err() is making a series of fragile assumptions that can lead to crashes: 1/ It assumes that endpoints identified in the record are a CXL-type-3 device, nothing guarantees that. 2/ It assumes that the device is bound to the cxl_pci driver, nothing guarantees that. 3/ Minor, it holds the device lock over the switch-port tracing for no reason as the trace is 100% generated from data in the record. Correct those by checking that the PCIe endpoint parents a cxl_memdev before assuming the format of the driver data, and move the lock to where it is required. Consequently this also makes the implementation ready for CXL accelerators that are not bound to cxl_pci.

References

• https://git.kernel.org/stable/c/4bcb8dd36e9e3fad6c22862ac5b6993df838309b
• https://git.kernel.org/stable/c/3c70ec71abdaf4e4fa48cd8fdfbbd864d78235a8