CVE-2024-44936 in Linux
Summary
by MITRE • 08/26/2024
In the Linux kernel, the following vulnerability has been resolved:
power: supply: rt5033: Bring back i2c_set_clientdata
Commit 3a93da231c12 ("power: supply: rt5033: Use devm_power_supply_register() helper") reworked the driver to use devm. While at it, the i2c_set_clientdata was dropped along with the remove callback. Unfortunately other parts of the driver also rely on i2c clientdata so this causes kernel oops.
Bring the call back to fix the driver.
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Analysis
by VulDB Data Team • 09/06/2024
The vulnerability CVE-2024-44936 represents a critical regression in the Linux kernel's power supply driver for the rt5033 device, specifically affecting the i2c client data management within the device driver framework. This issue stems from a seemingly straightforward refactoring that introduced a fundamental flaw in driver initialization and cleanup processes. The problem manifests when the driver attempts to access i2c client data that has been inadvertently removed during the transition to use devm_power_supply_register() helper function, leading to kernel oops and system instability.
The technical root cause of this vulnerability lies in the improper handling of device driver resource management during the refactoring process. The commit 3a93da231c12 attempted to modernize the driver by adopting the devm_power_supply_register() helper, which is designed to simplify device memory management and automatic cleanup. However, this refactoring process erroneously omitted the i2c_set_clientdata() call that was previously essential for maintaining device state information. The removal of this critical data management step created a disconnect between the driver's initialization logic and its operational requirements, as other components within the same driver still depend on accessing client data through the i2c subsystem.
This vulnerability directly impacts system stability and reliability, particularly in embedded systems and mobile devices that utilize the rt5033 power management chip. When the kernel attempts to access device data that no longer exists in the client data structure, it results in a kernel oops condition that can lead to system crashes, unexpected reboots, or complete system lockups. The operational impact extends beyond simple functionality loss, as this type of kernel-level instability can compromise the security posture of affected systems and potentially provide attackers with opportunities to exploit the system's instability for privilege escalation or denial of service attacks. The vulnerability affects systems running Linux kernel versions where the problematic commit was introduced, particularly those implementing power management for battery charging and power supply regulation.
The recommended mitigation strategy involves reverting the problematic commit or applying a targeted patch that reinstates the i2c_set_clientdata() call while maintaining the benefits of the devm_power_supply_register() helper. This approach ensures that the driver maintains proper access to client data while preserving the memory management improvements introduced in the refactoring. System administrators should prioritize applying kernel updates that address this specific vulnerability, particularly in production environments where system stability is critical. The fix aligns with best practices for device driver development and follows the principle of maintaining backward compatibility while implementing modern memory management techniques. Organizations should conduct thorough testing of kernel updates to ensure that the patch resolves the issue without introducing additional regressions, as the complexity of device driver interactions can sometimes create unexpected side effects. This vulnerability exemplifies the importance of comprehensive testing during kernel modifications and demonstrates how seemingly minor refactoring changes can have significant impacts on system stability and security.