CVE-2024-46844 in Linux
Summary
by MITRE • 09/27/2024
In the Linux kernel, the following vulnerability has been resolved:
um: line: always fill *error_out in setup_one_line()
The pointer isn't initialized by callers, but I have encountered cases where it's still printed; initialize it in all possible cases in setup_one_line().
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 04/05/2026
The vulnerability identified as CVE-2024-46844 resides within the Linux kernel's user memory management subsystem, specifically affecting the setup_one_line() function implementation. This issue represents a classic case of uninitialized memory access that could potentially lead to information disclosure or system instability. The flaw manifests when the error_out parameter pointer is not properly initialized by calling functions before being passed to setup_one_line(), creating a scenario where the function may attempt to dereference or print an uninitialized pointer value. The vulnerability is classified under CWE-457 as "Use of Uninitialized Variable" which directly impacts the integrity of memory management operations within kernel space. This type of vulnerability falls under the ATT&CK technique T1068 which involves exploiting local privileges to gain system-level access through kernel-level flaws.
The technical implementation of this vulnerability stems from the function setup_one_line() which processes memory allocation and error handling operations for user memory management. When callers of this function fail to initialize the error_out parameter properly, the function itself does not guarantee that this pointer will be set to a valid value before potential use. This creates a race condition where the pointer may contain arbitrary data from previous memory operations, leading to unpredictable behavior when the code attempts to print or process the uninitialized value. The kernel's memory management subsystem relies heavily on proper initialization of all parameters to maintain system stability and prevent information leakage that could be exploited by malicious actors. The fix implemented addresses this by ensuring that error_out is always populated with a valid value regardless of the code path taken within setup_one_line(), effectively preventing any potential information disclosure through uninitialized pointer dereferencing.
The operational impact of this vulnerability extends beyond simple memory management concerns as it represents a potential entry point for privilege escalation attacks within kernel space. When uninitialized pointers are processed in kernel functions, they may inadvertently expose kernel memory contents to user-space processes through error message outputs or logging mechanisms. This information disclosure could provide attackers with insights into kernel memory layout, which is particularly dangerous in systems where kernel memory addresses are randomized or where the attacker can leverage the leaked information for more sophisticated exploitation techniques. The vulnerability affects systems running Linux kernel versions where this specific function is implemented, potentially impacting a wide range of devices from servers to embedded systems that rely on proper kernel memory management. The exploitation of this vulnerability could lead to denial of service conditions or provide footholds for more advanced attacks that target kernel memory structures.
Mitigation strategies for CVE-2024-46844 focus primarily on applying the kernel patch that ensures proper initialization of the error_out parameter within setup_one_line(). System administrators should prioritize updating their kernel versions to include the fix, particularly in environments where kernel memory management is critical for system stability. The patch implementation follows standard security practices by ensuring that all function parameters are properly initialized before use, which aligns with the principle of least privilege and defensive programming. Organizations should also implement monitoring for any unusual error message patterns that might indicate the presence of uninitialized memory access, as this could serve as an early warning system for similar vulnerabilities. Additionally, regular kernel security audits should be conducted to identify and remediate similar issues in other kernel subsystems, particularly those involving memory management and error handling functions that operate in privileged contexts. The fix demonstrates the importance of proper parameter initialization in kernel code and reinforces the need for comprehensive testing of error handling paths in security-critical system components.