CVE-2026-53335 in Linux
Summary
by MITRE • 07/01/2026
In the Linux kernel, the following vulnerability has been resolved:
mm/damon/lru_sort: handle ctx allocation failure
DAMON_LRU_SORT allocates the damon_ctx object for its kdamond in its init function. damon_lru_sort_enabled_store() wrongly assumes the allocation will always succeed once tried. If the damon_ctx allocation was failed, therefore, code execution reaches to damon_commit_ctx() while 'ctx' is NULL. As a result, it dereferences the NULL 'ctx' pointer. Avoid the NULL dereference by returning -ENOMEM if 'ctx' is NULL.
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Analysis
by VulDB Data Team • 07/01/2026
The vulnerability under discussion relates to a critical null pointer dereference in the Linux kernel's DAMON (Dynamic Address Monitoring) subsystem, specifically within the LRU sort functionality. This issue resides in the mm/damon/lru_sort.c file where the damon_ctx object allocation process fails to properly handle memory allocation errors during kernel module initialization. The DAMON_LRU_SORT component is designed to monitor memory access patterns and optimize memory management through LRU (Least Recently Used) sorting techniques, making it an integral part of the kernel's memory management infrastructure.
The technical flaw manifests in the damon_lru_sort_enabled_store() function which contains a logical error in its error handling mechanism. During the initialization phase, this function attempts to allocate a damon_ctx object for the kdamond process but fails to account for potential allocation failures. The function assumes that once the allocation attempt is made, it will always succeed, creating a dangerous assumption that leads to subsequent code execution paths where NULL pointer dereference occurs. When memory allocation fails and returns NULL, the code continues execution without proper validation, leading directly to damon_commit_ctx() being called with a NULL context pointer.
This null pointer dereference represents a serious security vulnerability that can result in system instability and potential privilege escalation opportunities. The flaw creates an execution path where kernel memory management functions attempt to operate on invalid memory references, potentially leading to kernel oops, system crashes, or more severe consequences depending on the exploitation vector. From a cybersecurity perspective, this vulnerability aligns with CWE-476 which identifies null pointer dereference as a critical weakness in software systems, particularly within kernel space where such errors can compromise entire system integrity.
The operational impact of this vulnerability extends beyond simple system crashes to potentially enable malicious actors to exploit the kernel's memory management subsystem. Attackers could leverage this flaw to cause denial of service conditions or potentially gain elevated privileges through controlled memory corruption patterns. The vulnerability affects systems running Linux kernels that include the DAMON_LRU_SORT functionality, particularly those utilizing memory monitoring features for performance optimization or security analysis purposes.
The mitigation strategy involves implementing proper error handling within the damon_lru_sort_enabled_store() function to validate allocation results before proceeding with subsequent operations. The fix requires returning -ENOMEM when ctx is NULL to prevent the execution path that leads to null pointer dereference. This approach follows established kernel development practices for memory allocation error handling and aligns with ATT&CK framework's T1068 (Exploitation for Privilege Escalation) and T1499 (Endpoint Termination) techniques that target kernel-level vulnerabilities. The solution ensures that all kernel subsystems properly validate resource allocation states before proceeding with operations that depend on those resources, thereby maintaining system stability and preventing unauthorized access to kernel memory spaces.