CVE-2022-49484 in Linux
Summary
by MITRE • 02/26/2025
In the Linux kernel, the following vulnerability has been resolved:
mt76: mt7915: fix possible NULL pointer dereference in mt7915_mac_fill_rx_vector
Fix possible NULL pointer dereference in mt7915_mac_fill_rx_vector routine if the chip does not support dbdc and the hw reports band_idx set to 1.
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Analysis
by VulDB Data Team • 02/26/2025
The vulnerability identified as CVE-2022-49484 affects the Linux kernel's mt76 wireless driver specifically targeting the mt7915 chipset implementation. This issue manifests as a potential NULL pointer dereference within the mt7915_mac_fill_rx_vector function, representing a critical reliability concern that could compromise system stability. The flaw occurs when the hardware reports a band_idx value of 1 while the chip does not support dual-band dual-connection (dbdc) functionality, creating a condition where the driver attempts to access memory locations that have not been properly initialized or allocated.
The technical root cause stems from inadequate input validation and conditional logic within the wireless driver's receive vector processing routine. When the hardware abstraction layer reports a band index of 1, the driver assumes the hardware supports dbdc capabilities and proceeds to dereference pointers without verifying whether the underlying hardware actually possesses these features. This mismatch between hardware capability reporting and driver implementation creates a path where memory access violations can occur, potentially leading to kernel crashes or system instability. The vulnerability represents a classic example of improper error handling and resource management within kernel space code, where assumptions about hardware capabilities are not properly validated before memory operations are executed.
From an operational perspective, this vulnerability poses significant risks to systems utilizing mt7915 wireless chipsets, particularly in enterprise environments where wireless network stability is critical. The NULL pointer dereference could result in complete system crashes, requiring manual intervention and potentially leading to service disruption. Attackers could potentially exploit this vulnerability to cause denial of service conditions, especially in scenarios where wireless connectivity is essential for system operations. The impact extends beyond simple system instability as this flaw could be leveraged to create persistent availability issues in wireless network infrastructure, affecting both client devices and network access points. The vulnerability affects systems running Linux kernel versions that include the affected mt76 driver implementation, making it relevant to a wide range of network equipment and embedded systems.
Mitigation strategies should focus on applying the official kernel patch that resolves the NULL pointer dereference by adding proper conditional checks before pointer access. System administrators should prioritize updating to kernel versions containing the fix, typically kernel versions 5.19 and later where this vulnerability has been addressed. Additional protective measures include monitoring wireless network stability and implementing robust error handling within wireless network management systems. The fix aligns with security best practices outlined in the CWE-476 category for NULL pointer dereference vulnerabilities and follows ATT&CK technique T1499.004 for network denial of service attacks. Organizations should also consider implementing network segmentation and redundancy measures to minimize the impact of potential exploitation attempts. Regular kernel updates and security audits of wireless network infrastructure remain essential practices for maintaining system integrity and preventing exploitation of similar vulnerabilities in the wireless driver stack.