CVE-2021-47181 in Linux
Summary
by MITRE • 04/10/2024
In the Linux kernel, the following vulnerability has been resolved:
usb: musb: tusb6010: check return value after calling platform_get_resource()
It will cause null-ptr-deref if platform_get_resource() returns NULL, we need check the return value.
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Analysis
by VulDB Data Team • 12/20/2024
The vulnerability identified as CVE-2021-47181 resides within the Linux kernel's USB subsystem, specifically affecting the musb (multi-purpose USB) driver implementation for the tusb6010 controller. This flaw represents a classic null pointer dereference issue that emerges from inadequate error handling in device resource allocation procedures. The vulnerability occurs during the platform device resource acquisition phase where the kernel attempts to retrieve hardware resource information for USB controller initialization. When the platform_get_resource() function fails to locate or retrieve the necessary resource information, it returns a NULL pointer, which the vulnerable code fails to properly validate before proceeding with subsequent operations.
The technical implementation of this vulnerability stems from the absence of proper return value validation in the USB driver's resource management logic. The platform_get_resource() function serves as a critical interface for retrieving device tree or platform resource information including memory regions, interrupt lines, and other hardware-specific parameters required for USB controller operation. When this function returns NULL indicating resource acquisition failure, the subsequent code path proceeds without checking this condition, leading to a null pointer dereference when attempting to access the resource structure. This type of error falls under the common software vulnerability category classified as CWE-476, specifically Null Pointer Dereference, which represents one of the most prevalent and dangerous classes of software flaws in kernel space programming.
The operational impact of CVE-2021-47181 extends beyond simple system instability, potentially enabling denial of service conditions that can severely disrupt USB functionality on affected Linux systems. When a null pointer dereference occurs in kernel space, the immediate consequence is typically a system crash or kernel oops, which results in the complete failure of USB device operations and may require system reboot to restore normal functionality. This vulnerability affects systems utilizing the tusb6010 USB controller implementation within the musb driver framework, particularly those running Linux kernel versions prior to the security patch. The attack surface is limited to systems where USB devices are actively used and where the specific tusb6010 controller driver is loaded, but the impact remains significant given the critical nature of USB functionality in modern computing environments.
Mitigation strategies for CVE-2021-47181 focus primarily on applying the official kernel security patches that implement proper return value checking for platform_get_resource() calls. The fix involves adding conditional validation logic that explicitly checks whether platform_get_resource() returns NULL before proceeding with resource access operations. This approach aligns with the ATT&CK framework's defense evasion techniques by ensuring proper input validation and error handling within kernel modules. System administrators should prioritize updating to kernel versions containing the patched musb driver implementation, typically found in kernel releases 5.13 and later. Additionally, organizations should implement comprehensive patch management procedures to ensure all systems utilizing USB functionality remain protected against this class of vulnerability. The remediation process also includes verifying that the updated kernel properly handles edge cases in device tree parsing and resource allocation, particularly in virtualized environments where platform resource information may be dynamically provisioned.