9d573d1954
Ricky reports that replacing a device in a hotplug slot during ACPI sleep state S3 does not cause re-enumeration on resume, as one would expect. Instead, the new device is treated as if it was the old one. There is no bulletproof way to detect device replacement, but as a heuristic, check whether the device identity in config space matches cached data in struct pci_dev (Vendor ID, Device ID, Class Code, Revision ID, Subsystem Vendor ID, Subsystem ID). Additionally, cache and compare the Device Serial Number (PCIe r6.2 sec 7.9.3). If a mismatch is detected, mark the old device disconnected (to prevent its driver from accessing the new device) and synthesize a Presence Detect Changed event. The device identity in config space which is compared here is the same as the one included in the signed Subject Alternative Name per PCIe r6.1 sec 6.31.3. Thus, the present commit prevents attacks where a valid device is replaced with a malicious device during system sleep and the valid device's driver obliviously accesses the malicious device. This is about as much as can be done at the PCI layer. Drivers may have additional ways to identify devices (such as reading a WWID from some register) and may trigger re-enumeration when detecting an identity change on resume. Link: https://lore.kernel.org/r/a1afaa12f341d146ecbea27c1743661c71683833.1716992815.git.lukas@wunner.de Reported-by: Ricky Wu <ricky_wu@realtek.com> Closes: https://lore.kernel.org/r/a608b5930d0a48f092f717c0e137454b@realtek.com Tested-by: Ricky Wu <ricky_wu@realtek.com> Signed-off-by: Lukas Wunner <lukas@wunner.de> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.