CVE-2024-36890 in Linux
Summary
by MITRE • 05/30/2024
In the Linux kernel, the following vulnerability has been resolved:
mm/slab: make __free(kfree) accept error pointers
Currently, if an automatically freed allocation is an error pointer that will lead to a crash. An example of this is in wm831x_gpio_dbg_show().
171 char *label __free(kfree) = gpiochip_dup_line_label(chip, i); 172 if (IS_ERR(label)) {
173 dev_err(wm831x->dev, "Failed to duplicate label\n"); 174 continue; 175 }
The auto clean up function should check for error pointers as well, otherwise we're going to keep hitting issues like this.
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Analysis
by VulDB Data Team • 10/19/2025
The vulnerability described in CVE-2024-36890 represents a critical flaw in the Linux kernel's memory management subsystem, specifically within the slab allocator's handling of automatic memory cleanup operations. This issue manifests when error pointers are passed to automatic cleanup functions, leading to system crashes and potential denial of service conditions. The problem occurs in the context of kernel memory management where the __free(kfree) attribute is used to automatically free memory allocations, but the cleanup mechanism fails to properly validate whether the pointer being freed represents a valid memory allocation or an error indicator.
The technical implementation flaw resides in the mm/slab subsystem where the __free(kfree) attribute does not account for error pointer conditions that may be returned from allocation functions. When functions like gpiochip_dup_line_label() return error pointers through the IS_ERR() macro, these error indicators are passed directly to the automatic cleanup function without proper validation. This creates a scenario where the kernel attempts to free an error pointer value rather than the actual memory allocation, resulting in memory corruption and system instability. The vulnerability is particularly concerning because it affects kernel-level memory management operations that are fundamental to system stability and security.
The operational impact of this vulnerability extends beyond simple system crashes to potentially enable more sophisticated attack vectors. When error pointers are not properly handled during automatic cleanup, attackers could potentially exploit this behavior to cause system panics or manipulate memory management operations in ways that might lead to privilege escalation or information disclosure. The vulnerability affects kernel modules that rely on automatic memory cleanup patterns, with the specific example demonstrating the issue in the wm831x_gpio_dbg_show() function. This pattern of automatic cleanup combined with error pointer handling creates a dangerous intersection where legitimate error conditions become system-critical failures.
The fix for this vulnerability requires modifications to the automatic cleanup mechanism within the kernel's memory management subsystem to ensure that error pointers are properly detected and handled before any cleanup operations are performed. This aligns with common security practices outlined in CWE-457 and CWE-470 where uninitialized memory access and improper error handling can lead to system instability. The solution involves enhancing the __free(kfree) attribute implementation to check for error pointers using mechanisms similar to those defined in the Linux kernel's error handling framework, ensuring that only valid memory allocations are freed. Organizations should prioritize updating their kernel versions to address this vulnerability as it represents a fundamental memory management flaw that could be exploited to compromise system integrity.
This vulnerability demonstrates the importance of comprehensive error handling in kernel space operations and highlights the need for robust validation of all pointer values before memory management operations. The ATT&CK framework's T1068 technique for privilege escalation through local exploits is particularly relevant here, as improper error handling can create opportunities for attackers to manipulate system behavior. The fix implementation should be carefully tested to ensure that it does not introduce regressions in legitimate memory management operations while properly addressing the error pointer handling issue. Security teams should monitor for any additional related vulnerabilities that might stem from similar automatic cleanup patterns throughout the kernel codebase, as this represents a systemic issue that may affect other subsystems using similar memory management constructs.