Products

Linux kernel

• 6.3

• 5.10+

Source

416baaa9-dc9f-4396-8d5f-8c081fb06d67

Published : Aug. 17, 2024, 9:15 a.m.
Last Modified : Aug. 17, 2024, 9:15 a.m.

Description

In the Linux kernel, the following vulnerability has been resolved: PCI/DPC: Fix use-after-free on concurrent DPC and hot-removal Keith reports a use-after-free when a DPC event occurs concurrently to hot-removal of the same portion of the hierarchy: The dpc_handler() awaits readiness of the secondary bus below the Downstream Port where the DPC event occurred. To do so, it polls the config space of the first child device on the secondary bus. If that child device is concurrently removed, accesses to its struct pci_dev cause the kernel to oops. That's because pci_bridge_wait_for_secondary_bus() neglects to hold a reference on the child device. Before v6.3, the function was only called on resume from system sleep or on runtime resume. Holding a reference wasn't necessary back then because the pciehp IRQ thread could never run concurrently. (On resume from system sleep, IRQs are not enabled until after the resume_noirq phase. And runtime resume is always awaited before a PCI device is removed.) However starting with v6.3, pci_bridge_wait_for_secondary_bus() is also called on a DPC event. Commit 53b54ad074de ("PCI/DPC: Await readiness of secondary bus after reset"), which introduced that, failed to appreciate that pci_bridge_wait_for_secondary_bus() now needs to hold a reference on the child device because dpc_handler() and pciehp may indeed run concurrently. The commit was backported to v5.10+ stable kernels, so that's the oldest one affected. Add the missing reference acquisition. Abridged stack trace: BUG: unable to handle page fault for address: 00000000091400c0 CPU: 15 PID: 2464 Comm: irq/53-pcie-dpc 6.9.0 RIP: pci_bus_read_config_dword+0x17/0x50 pci_dev_wait() pci_bridge_wait_for_secondary_bus() dpc_reset_link() pcie_do_recovery() dpc_handler()

References

URL	Source
https://git.kernel.org/stable/c/11a1f4bc47362700fcbde717292158873fb847ed	416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/2cc8973bdc4d6c928ebe38b88090a2cdfe81f42f	416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/b16f3ea1db47a6766a9f1169244cf1fc287a7c62	416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/f63df70b439bb8331358a306541893bf415bf1da	416baaa9-dc9f-4396-8d5f-8c081fb06d67