CVE-2021-47409 in Linux
Summary
by MITRE • 05/21/2024
In the Linux kernel, the following vulnerability has been resolved:
usb: dwc2: 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 • 08/21/2025
The vulnerability identified as CVE-2021-47409 resides within the Linux kernel's USB device driver subsystem, specifically affecting the DesignWare USB2 Controller (dwc2) driver implementation. This issue represents a classic null pointer dereference vulnerability that can lead to system instability and potential privilege escalation. The flaw manifests in the driver's handling of platform resource acquisition during device initialization, where the kernel fails to properly validate the return value from the platform_get_resource() function before proceeding with subsequent operations. This type of vulnerability falls under the category of improper error handling and can be classified as CWE-476 according to the Common Weakness Enumeration standards.
The technical execution of this vulnerability occurs when the dwc2 driver attempts to initialize a USB controller on embedded platforms that utilize platform-specific resource management. During this initialization phase, the driver invokes platform_get_resource() to obtain memory or I/O resource information required for controller operation. When platform_get_resource() returns NULL indicating that no valid resource information could be obtained, the driver continues execution without proper validation, leading to a null pointer dereference when attempting to access the uninitialized resource structure. This condition typically results in immediate system crash or kernel panic, rendering the affected system non-functional until reboot occurs. The vulnerability demonstrates characteristics consistent with ATT&CK technique T1068 which involves exploiting local privilege escalation opportunities through kernel-level flaws.
The operational impact of CVE-2021-47409 extends beyond simple system instability to potentially compromise entire embedded systems and devices running affected kernel versions. Devices utilizing DesignWare USB2 controllers such as various embedded systems, network appliances, and IoT devices may become vulnerable to denial of service attacks that can be triggered by connecting malicious USB devices or by manipulating the platform device tree configuration. The vulnerability affects Linux kernel versions prior to the patch release that addressed this specific issue, making it particularly concerning for embedded systems that may not receive regular kernel updates. Attackers could potentially exploit this vulnerability to cause system crashes, leading to availability disruptions, or in more sophisticated scenarios, leverage the kernel crash conditions to execute arbitrary code with kernel privileges. The lack of proper input validation in this critical kernel driver component creates a significant attack surface that can be exploited by both local and potentially remote adversaries depending on the system configuration and attack vectors available. Mitigation strategies include updating to kernel versions containing the fix, implementing proper resource validation checks in custom driver modifications, and applying runtime protections through kernel lockdown mechanisms or other security hardening measures that can prevent exploitation of such kernel-level vulnerabilities.