CVE-2021-34405 in Shield TV
Summary
by MITRE • 01/18/2022
NVIDIA Linux distributions contain a vulnerability in TrustZone’s TEE_Malloc function, where an unchecked return value causing a null pointer dereference may lead to denial of service.
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Analysis
by VulDB Data Team • 01/20/2022
The vulnerability identified as CVE-2021-34405 resides within NVIDIA's Linux distributions and specifically targets the TrustZone Trusted Execution Environment TEE_Malloc function. This flaw represents a critical security weakness that arises from improper error handling within the secure memory allocation mechanism. The issue manifests when the TEE_Malloc function fails to properly validate return values from underlying memory allocation calls, creating a scenario where subsequent operations attempt to dereference null pointers. This particular vulnerability falls under the category of improper error handling as classified by CWE-252, which specifically addresses conditions where error codes are not properly checked or handled. The vulnerability affects NVIDIA's implementation of the Trusted Execution Environment on Linux systems, which provides a secure execution environment for sensitive operations and data processing.
The technical exploitation of this vulnerability occurs when the TEE_Malloc function encounters a memory allocation failure but fails to check the return value from the allocation call. When memory allocation fails, the function typically returns a null pointer, but in this case, the code does not validate this condition before proceeding with operations that assume valid memory allocation. This oversight creates a path where a null pointer dereference can occur, leading to an immediate system crash or termination of the Trusted Execution Environment component. The vulnerability is particularly concerning because it affects the core memory management functions of the secure environment, potentially compromising the integrity of security-sensitive operations that depend on the TEE's stability. The flaw is categorized as a denial of service condition because successful exploitation results in the complete unavailability of the TEE functionality, preventing legitimate users from accessing secure services.
The operational impact of CVE-2021-34405 extends beyond simple system downtime, as it fundamentally undermines the security posture of devices running NVIDIA's Linux distributions with TrustZone implementations. Systems that rely on the TEE for secure boot processes, cryptographic operations, or secure key storage become vulnerable to complete service disruption. This vulnerability affects a wide range of embedded systems, automotive platforms, and mobile devices that utilize NVIDIA's hardware security modules. The potential for exploitation is relatively straightforward since it requires only triggering a memory allocation failure condition within the TEE environment, which can be achieved through resource exhaustion or other means that cause allocation failures. Organizations using affected NVIDIA hardware may experience complete service outages for security-critical functions, particularly in environments where the TEE is essential for maintaining secure operations.
Mitigation strategies for this vulnerability require immediate attention and systematic implementation across affected systems. The primary recommendation involves applying the official NVIDIA security patches that address the unchecked return value issue in the TEE_Malloc function. System administrators should prioritize updating their NVIDIA Linux distributions to versions that include the corrected error handling mechanisms. Additionally, monitoring systems should be enhanced to detect unusual memory allocation patterns or TEE service disruptions that could indicate exploitation attempts. The vulnerability demonstrates the importance of proper error handling in security-critical code paths as highlighted by ATT&CK technique T1489, which covers denial of service through manipulation of system resources. Organizations should also consider implementing additional runtime protections such as memory protection mechanisms and secure coding practices that enforce proper validation of all return values from system calls. The fix typically involves adding explicit null pointer checks after memory allocation calls within the TEE_Malloc implementation, ensuring that all error conditions are properly handled before proceeding with subsequent operations that might lead to system instability or security compromise.