CVE-2022-50847 in Linux
Summary
by MITRE • 12/30/2025
In the Linux kernel, the following vulnerability has been resolved:
drm/bridge: it6505: Initialize AUX channel in it6505_i2c_probe
During device boot, the HPD interrupt could be triggered before the DRM subsystem registers it6505 as a DRM bridge. In such cases, the driver tries to access AUX channel and causes NULL pointer dereference. Initializing the AUX channel earlier to prevent such error.
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Analysis
by VulDB Data Team • 04/26/2026
The vulnerability identified as CVE-2022-50847 resides within the Linux kernel's display subsystem, specifically affecting the it6505 display bridge driver. This issue manifests as a null pointer dereference condition that occurs during system boot sequences when hot-plug detection (HPD) interrupts are triggered prematurely. The root cause stems from the timing dependency between hardware interrupt handling and driver initialization processes, creating a race condition that can lead to system instability and potential crashes.
The technical flaw exists in the drm/bridge/it6505 driver implementation where the auxiliary channel (AUX) communication interface is not properly initialized before the HPD interrupt handler attempts to access it. This represents a classic initialization ordering problem that violates fundamental software engineering principles and can be classified under CWE-476 as a null pointer dereference. The driver's it6505_i2c_probe function fails to establish the AUX channel early enough in the boot process, leaving the communication interface in an uninitialized state when interrupt handlers attempt to utilize it for display protocol communications.
During normal operation, the it6505 bridge driver must establish proper communication channels before responding to hot-plug events. However, when the system boots, HPD interrupts can be generated before the DRM subsystem completes its registration process for the it6505 device. This timing discrepancy causes the interrupt handler to attempt access to an uninitialized AUX channel structure, resulting in a kernel panic or system crash. The vulnerability demonstrates a clear breakdown in the driver's initialization sequence and failure to properly handle asynchronous events during boot.
The operational impact of this vulnerability extends beyond simple system crashes to potentially compromise the entire display functionality of affected systems. When triggered, the null pointer dereference can cause complete system lockups, requiring manual intervention or reboot to restore normal operation. This is particularly concerning in embedded systems or devices where automatic recovery mechanisms may not be available, and system uptime is critical. The vulnerability affects any Linux system utilizing the it6505 display bridge controller, making it relevant to a wide range of hardware platforms including desktop computers, laptops, and embedded display solutions.
Mitigation strategies for CVE-2022-50847 involve implementing proper initialization ordering within the driver code to ensure the AUX channel is established before any interrupt handlers can access it. The fix requires modifying the it6505_i2c_probe function to initialize the auxiliary channel structure during early driver setup, before registering interrupt handlers or completing the DRM bridge registration process. This approach aligns with the ATT&CK framework's defensive techniques for kernel-level security by addressing initialization timing issues that could be exploited by malicious actors. System administrators should ensure all affected systems are updated with patched kernel versions that implement this fix, as the vulnerability can be triggered by normal boot sequences without any malicious input or specific attack conditions.