CVE-2024-26650

Published: 26 March 2024

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 <klarasmodin@gmail.com>

Status

References

• https://git.kernel.org/linus/5913320eb0b3ec88158cfcb0fa5e996bf4ef681b (6.8-rc2)
• https://git.kernel.org/stable/c/2841631a03652f32b595c563695d0461072e0de4
• https://git.kernel.org/stable/c/847e1eb30e269a094da046c08273abe3f3361cf2
• https://git.kernel.org/stable/c/d281ac9a987c553d93211b90fd4fe97d8eca32cd
• https://git.kernel.org/stable/c/5913320eb0b3ec88158cfcb0fa5e996bf4ef681b
• https://www.cve.org/CVERecord?id=CVE-2024-26650
• NVD
• Launchpad
• Debian