CVE-2024-39479
Description
From CVE.org
In the Linux kernel, the following vulnerability has been resolved: drm/i915/hwmon: Get rid of devm When both hwmon and hwmon drvdata (on which hwmon depends) are device managed resources, the expectation, on device unbind, is that hwmon will be released before drvdata. However, in i915 there are two separate code paths, which both release either drvdata or hwmon and either can be released before the other. These code paths (for device unbind) are as follows (see also the bug referenced below): Call Trace: release_nodes+0x11/0x70 devres_release_group+0xb2/0x110 component_unbind_all+0x8d/0xa0 component_del+0xa5/0x140 intel_pxp_tee_component_fini+0x29/0x40 [i915] intel_pxp_fini+0x33/0x80 [i915] i915_driver_remove+0x4c/0x120 [i915] i915_pci_remove+0x19/0x30 [i915] pci_device_remove+0x32/0xa0 device_release_driver_internal+0x19c/0x200 unbind_store+0x9c/0xb0 and Call Trace: release_nodes+0x11/0x70 devres_release_all+0x8a/0xc0 device_unbind_cleanup+0x9/0x70 device_release_driver_internal+0x1c1/0x200 unbind_store+0x9c/0xb0 This means that in i915, if use devm, we cannot gurantee that hwmon will always be released before drvdata. Which means that we have a uaf if hwmon sysfs is accessed when drvdata has been released but hwmon hasn't. The only way out of this seems to be do get rid of devm_ and release/free everything explicitly during device unbind. v2: Change commit message and other minor code changes v3: Cleanup from i915_hwmon_register on error (Armin Wolf) v4: Eliminate potential static analyzer warning (Rodrigo) Eliminate fetch_and_zero (Jani) v5: Restore previous logic for ddat_gt->hwmon_dev error return (Andi)
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 4.4 | 7.8 | 7.8 |
| Attack Vector | Local | Local | Local |
| Attack Complexity | Low | Low | Low |
| Privileges Required | High | Low | Low |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | None | High | High |
| Integrity Impact | None | High | High |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory
The use of previously freed memory may corrupt valid data, if the memory area in question has been allocated and used properly elsewhere.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If chunk consolidation occurs after the use of previously freed data, the process may crash when invalid data is used as chunk information.
Confidentiality
Technical Impact: Read Memory
Read operations on freed memory can sometimes leak sensitive information instead of causing a crash
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If malicious data is entered before chunk consolidation can take place, it may be possible to take advantage of a write-what-where primitive to execute arbitrary code. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.
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