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

2024-06-2413:56:51

Linux

www.cve.org

linux kernel

fpga bridge

module owner

refcount

null pointer dereference

0.0004 Low

EPSS

Percentile

15.6%

JSON

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.

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "Documentation/driver-api/fpga/fpga-bridge.rst",
      "drivers/fpga/fpga-bridge.c",
      "include/linux/fpga/fpga-bridge.h"
    ],
    "versions": [
      {
        "version": "21aeda950c5f",
        "lessThan": "d7c4081c54a1",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "21aeda950c5f",
        "lessThan": "6896b6b2e2d9",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "21aeda950c5f",
        "lessThan": "1da11f822042",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "Documentation/driver-api/fpga/fpga-bridge.rst",
      "drivers/fpga/fpga-bridge.c",
      "include/linux/fpga/fpga-bridge.h"
    ],
    "versions": [
      {
        "version": "4.10",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "4.10",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.6.33",
        "lessThanOrEqual": "6.6.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.9.4",
        "lessThanOrEqual": "6.9.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.10-rc1",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]