CVE-2026-93156 in Linux
Summary
by MITRE • 09/18/2026
In the Linux kernel, the following vulnerability has been resolved:
crypto: rk3288 - fail ahash requests on HASH idle timeout
rk_hash_run() waits for RK_CRYPTO_HASH_STS to become idle after the final DMA transfer, but ignores the poll result. If the hash engine never becomes idle, the driver still reads the digest registers and finalizes the request with the previous success value.
Store the poll result and finalize the request with the timeout error before reading the digest registers.
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Analysis
by VulDB Data Team • 09/18/2026
The Linux kernel cryptographic subsystem for Rockchip SoCs contains a critical flaw in its asynchronous hash implementation that can lead to data integrity issues and potential security vulnerabilities due to improper handling of hardware timeouts. The vulnerability resides within the rk_hash_run function, which is responsible for managing the lifecycle of hash operations on devices such as the RK3288. During normal operation, this function initiates a DMA transfer to process input data through the hardware cryptographic engine and subsequently waits for the HASH status register to indicate that the device has returned to an idle state. This polling mechanism is essential to ensure that all computational results are fully committed by the hardware before the driver attempts to retrieve them from the digest registers.
The core technical flaw lies in the fact that while the code correctly initiates a wait loop for the HASH status register, it completely ignores the return value of this poll operation. If the cryptographic engine fails to become idle within the expected timeframe due to a hardware fault, system load, or other transient errors, the driver proceeds as if the operation was successful. Consequently, the software continues to read from the digest registers and finalizes the request with a success status code rather than reporting an error. This behavior results in the application receiving potentially stale, partial, or corrupted hash output data while being misled into believing that the cryptographic computation completed correctly.
From a security perspective, this vulnerability falls under CWE-362, which describes concurrent execution using shared resources without proper synchronization, although it is more accurately characterized by CWE-754: Improper Check for Unusual or Exceptional Conditions and CWE-20: Improper Input Validation in the context of hardware state verification. The failure to validate the operational status of a critical security component means that downstream applications relying on these hashes for integrity checks, authentication tokens, or digital signatures may operate with false confidence. In scenarios where hash values are used to verify file integrity or authenticate system components, accepting incorrect results could allow malicious actors to bypass security controls if they can induce conditions that cause the hardware timeout, although exploiting this typically requires local access and specific timing conditions.
The operational impact of this flaw is significant for systems relying on Rockchip-based devices for cryptographic operations in high-load environments where hardware responsiveness might be compromised. Applications performing bulk data hashing or real-time authentication may silently accept invalid results, leading to undetected data corruption or security breaches. For instance, if a file verification process uses the flawed hash output, it might incorrectly validate a tampered file as authentic because the driver reported success despite the engine failing to complete the calculation properly. This undermines the fundamental trust model of cryptographic operations where correctness is paramount.
To mitigate this vulnerability, the Linux kernel maintainers have implemented a fix that stores the result of the poll operation and checks for timeout conditions before proceeding with digest retrieval. If the hardware fails to become idle within the allotted time, the driver now correctly finalizes the request with an error code rather than a success value. This ensures that applications are immediately notified of the failure and can handle it appropriately, such as by retrying the operation or logging the incident for further investigation. System administrators should ensure their kernels are updated to include this patch, particularly on devices utilizing Rockchip RK3288 or similar SoCs with integrated cryptographic accelerators. Regular updates to the kernel crypto subsystem are essential to maintain the integrity of hardware-assisted security features and prevent silent failures in critical data processing pipelines.