CVE-2022-48928 in Linux
Summary
by MITRE • 08/22/2024
In the Linux kernel, the following vulnerability has been resolved:
iio: adc: men_z188_adc: Fix a resource leak in an error handling path
If iio_device_register() fails, a previous ioremap() is left unbalanced.
Update the error handling path and add the missing iounmap() call, as already done in the remove function.
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Analysis
by VulDB Data Team • 08/23/2024
The vulnerability identified as CVE-2022-48928 represents a resource management flaw within the Linux kernel's Industrial I/O (IIO) subsystem, specifically affecting the men_z188_adc driver. This issue resides in the hardware abstraction layer responsible for managing analog-to-digital conversions in embedded systems. The flaw manifests when the iio_device_register() function encounters an error during device registration, creating a critical imbalance in memory mapping operations that can lead to system instability and resource exhaustion.
The technical root cause of this vulnerability stems from improper error handling within the driver's initialization sequence. When iio_device_register() fails to complete successfully, the driver continues execution without properly cleaning up resources that were allocated during the setup process. Specifically, the ioremap() function, which maps physical memory addresses to virtual addresses for device access, is called but never subsequently undone by the corresponding iounmap() function. This creates a memory mapping leak that persists until the system reboots or the driver is unloaded, effectively consuming kernel virtual memory resources that should be reclaimed.
This resource leak vulnerability directly impacts system stability and can be exploited to cause denial of service conditions within embedded systems that rely on the men_z188_adc driver for analog input processing. The operational consequences extend beyond simple memory consumption as the accumulation of leaked mappings can eventually exhaust available virtual memory space, leading to system crashes or degraded performance in resource-constrained environments. The vulnerability is particularly concerning in industrial automation and embedded computing scenarios where system reliability is paramount and unexpected resource exhaustion could lead to critical operational failures.
The fix implemented for CVE-2022-48928 addresses the issue by modifying the error handling path to ensure proper cleanup of memory mappings. The solution involves adding the missing iounmap() call in the error handling code path, aligning it with the existing cleanup pattern already implemented in the driver's remove function. This remediation follows established kernel development practices and aligns with the principle of resource acquisition is initialization where resources are properly released regardless of execution flow. The fix demonstrates adherence to the CWE-404 weakness category, which specifically addresses improper resource management and failure to release resources, making it consistent with industry standards for secure kernel development practices.
Security implications of this vulnerability extend to potential exploitation by malicious actors who could repeatedly trigger the error condition to exhaust system resources, effectively creating a denial of service attack vector. The ATT&CK framework categorizes this as a resource exhaustion technique that could be leveraged in systems where the men_z188_adc driver is present. The vulnerability affects Linux kernel versions prior to the patch release, making systems running affected kernel versions susceptible to this memory mapping leak that could be exploited in embedded environments. The fix ensures that all code paths properly clean up memory mappings, maintaining the kernel's memory management integrity and preventing the accumulation of leaked resources that could impact system stability and performance over time.