CVE-2022-50535 in Linux
Summary
by MITRE • 10/07/2025
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Fix potential null-deref in dm_resume
[Why]
Fixing smatch error: dm_resume() error: we previously assumed 'aconnector->dc_link' could be null
[How]
Check if dc_link null at the beginning of the loop, so further checks can be dropped.
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Analysis
by VulDB Data Team • 04/19/2026
The vulnerability identified as CVE-2022-50535 resides within the Linux kernel's display subsystem, specifically affecting the AMD display driver component known as drm/amd/display. This issue manifests as a potential null pointer dereference during the dm_resume function execution, which occurs when the system resumes from a suspended state. The flaw represents a classic software error pattern that can lead to system instability and potential denial of service conditions. The vulnerability was detected through static analysis tools like smatch, which identified an unsafe assumption in the code logic regarding pointer validation.
The technical root cause of this vulnerability stems from an improper null pointer check within the dm_resume function implementation. Previously, the code assumed that the 'aconnector->dc_link' pointer would never be null during the execution flow, which proved to be a faulty assumption under certain system conditions. This assumption led to a scenario where the driver could attempt to dereference a null pointer, resulting in a kernel panic or system crash. The vulnerability specifically impacts the AMD display driver's ability to properly handle display connector states during system resume operations, particularly when dealing with display links that may not have been fully initialized or have been removed from the system.
The operational impact of this vulnerability extends beyond simple system crashes, as it affects the reliability and stability of systems running Linux kernels with AMD graphics hardware. When triggered, the null pointer dereference can cause complete system hang or reboot, disrupting user sessions and potentially leading to data loss. This vulnerability is particularly concerning in server environments or embedded systems where uninterrupted operation is critical. The issue demonstrates a failure in proper error handling and defensive programming practices within the graphics driver code, where the expected state of system resources was not adequately validated before access.
The fix implemented for CVE-2022-50535 involves adding an explicit null pointer check at the beginning of the loop structure within the dm_resume function. This approach follows the principle of defensive programming by validating all pointer assumptions before attempting to use them. The solution eliminates the need for subsequent null checks within the loop by establishing the validation upfront, thereby reducing code complexity and improving maintainability. This fix aligns with common software security practices and addresses the underlying CWE category related to improper handling of null values. The resolution also demonstrates adherence to security best practices that would be categorized under ATT&CK techniques related to system service manipulation and kernel-level privilege escalation. The patched implementation ensures that display connector resume operations can safely handle cases where display links may be in an uninitialized or removed state, preventing the kernel from crashing during system resume sequences.