CVE-2024-42118 in Linux
Summary
by MITRE • 07/30/2024
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Do not return negative stream id for array
[WHY]
resource_stream_to_stream_idx returns an array index and it return -1 when not found; however, -1 is not a valid array index number.
[HOW]
When this happens, call ASSERT(), and return a zero instead.
This fixes an OVERRUN and an NEGATIVE_RETURNS issues reported by Coverity.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 09/29/2025
The vulnerability identified as CVE-2024-42118 resides within the Linux kernel's AMD display subsystem, specifically affecting the drm/amd/display driver component. This issue manifests in the resource_stream_to_stream_idx function which serves as a critical interface for managing display stream resources within the graphics subsystem. The flaw represents a fundamental logic error where the function attempts to return a negative value as an array index, creating a direct contradiction with the fundamental requirements of array indexing operations.
The technical flaw occurs when the resource_stream_to_stream_idx function fails to locate a matching stream within its internal array structure and appropriately returns -1 to indicate "not found" status. However, this negative return value violates the basic principle that array indices must be non-negative integers representing valid memory positions. The function's design fails to properly handle this edge case, leading to an invalid array access pattern that can cause unpredictable behavior in the display subsystem. This particular issue falls under CWE-129 which addresses improper validation of array indices, and more specifically aligns with CWE-191 which deals with integer underflow conditions that can result in negative values being used where positive indices are required.
The operational impact of this vulnerability extends beyond simple code correctness issues to potentially compromise system stability and security. When the function returns -1 instead of a valid array index, subsequent operations that use this value as an array subscript can trigger memory access violations, buffer overruns, or other undefined behaviors that may lead to system crashes or potential privilege escalation opportunities. The vulnerability was identified through static analysis tools like Coverity which detected both an overrun condition and a negative return value issue, indicating that the problematic code path could result in memory corruption when the negative value is used in array operations. This type of error demonstrates the intersection of CWE-129 and CWE-191 vulnerabilities, where improper bounds checking leads to negative values being used as array indices, creating a potential attack surface for malicious actors.
The mitigation strategy for CVE-2024-42118 involves implementing proper error handling within the resource_stream_to_stream_idx function by adding an assertion check to validate that the returned index is non-negative before proceeding with array operations. When the function encounters a situation where it would return -1, the code should instead return zero or implement proper error propagation mechanisms. This approach aligns with ATT&CK technique T1059.007 which involves the use of system commands and scripting languages, as the fix ensures proper validation of return values before they are used in critical system operations. The implementation should also include proper logging mechanisms to track when such edge cases occur, enabling system administrators to monitor for potential exploitation attempts or system instability. The fix directly addresses the root cause by ensuring that array indices remain within valid bounds and prevents the propagation of invalid negative values that could compromise system integrity.