CVE-2024-26650

In the Linux kernel, the following vulnerability has been resolved:
platform/x86: p2sb: Allow p2sb_bar() calls during PCI device probe
p2sb_bar() unhides P2SB device to get resources from the device. It guards
the operation by locking pci_rescan_remove_lock so that parallel rescans do
not find the P2SB device. However, this lock causes deadlock when PCI bus
rescan is triggered by /sys/bus/pci/rescan. The rescan locks
pci_rescan_remove_lock and probes PCI devices. When PCI devices call
p2sb_bar() during probe, it locks pci_rescan_remove_lock again. Hence the
deadlock. To avoid the deadlock, do not lock pci_rescan_remove_lock in
p2sb_bar(). Instead, do the lock at fs_initcall. Introduce
p2sb_cache_resources() for fs_initcall which gets and caches the P2SB
resources. At p2sb_bar(), refer the cache and return to the caller. Before
operating the device at P2SB DEVFN for resource cache, check that its
device class is PCI_CLASS_MEMORY_OTHER 0x0580 that PCH specifications
define. This avoids unexpected operation to other devices at the same
DEVFN. Tested-by Klara Modin <[email protected]>

Notes