CVE-2024-58006

In the Linux kernel, the following vulnerability has been resolved:

PCI: dwc: ep: Prevent changing BAR size/flags in pci_epc_set_bar()

In commit 4284c88fff0e ("PCI: designware-ep: Allow pci_epc_set_bar() update

inbound map address") set_bar() was modified to support dynamically

changing the backing physical address of a BAR that was already configured.

This means that set_bar() can be called twice, without ever calling

clear_bar() (as calling clear_bar() would clear the BAR's PCI address

assigned by the host).

This can only be done if the new BAR size/flags does not differ from the

existing BAR configuration. Add these missing checks.

If we allow set_bar() to set e.g. a new BAR size that differs from the

existing BAR size, the new address translation range will be smaller than

the BAR size already determined by the host, which would mean that a read

past the new BAR size would pass the iATU untranslated, which could allow

the host to read memory not belonging to the new struct pci_epf_bar.

While at it, add comments which clarifies the support for dynamically

changing the physical address of a BAR. (Which was also missing.)