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.

Classification

CVE ID: CVE-2024-36479

Affected Products

Vendor: Linux

Product: Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.04% (probability of being exploited)

EPSS Percentile: 5.08% (scored less or equal to compared to others)

EPSS Date: 2025-02-04 (when was this score calculated)

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

Timeline