CVE-2024-36479fpga: bridge: add owner module and take its refcount

Official description

In the Linux kernel, the following vulnerability has been resolved: fpga: bridge: add owner module and take its refcount The current implementation of the fpga bridge assumes that the low-level module registers a driver for the parent device and uses its owner pointer to take the module's refcount. This approach is problematic since it can lead to a null pointer dereference while attempting to get the bridge if the parent device does not have a driver. To address this problem, add a module owner pointer to the fpga_bridge struct and use it to take the module's refcount. Modify the function for registering a bridge to take an additional owner module parameter and rename it to avoid conflicts. Use the old function name for a helper macro that automatically sets the module that registers the bridge as the owner. This ensures compatibility with existing low-level control modules and reduces the chances of registering a bridge without setting the owner. Also, update the documentation to keep it consistent with the new interface for registering an fpga bridge. Other changes: opportunistically move put_device() from __fpga_bridge_get() to fpga_bridge_get() and of_fpga_bridge_get() to improve code clarity since the bridge device is taken in these functions.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/18dc8366abb6cadcb77668b1a16434654e355d49
• https://git.kernel.org/stable/c/d7c4081c54a1d4068de9440957303a76f9e5c95b
• https://git.kernel.org/stable/c/6896b6b2e2d9ec4e1b0acb4c1698a75a4b34d125
• https://git.kernel.org/stable/c/1da11f822042eb6ef4b6064dc048f157a7852529
• https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html