CVE-2024-43888 in Linux
Summary
by MITRE • 08/26/2024
In the Linux kernel, the following vulnerability has been resolved:
mm: list_lru: fix UAF for memory cgroup
The mem_cgroup_from_slab_obj() is supposed to be called under rcu lock or cgroup_mutex or others which could prevent returned memcg from being freed. Fix it by adding missing rcu read lock.
Found by code inspection.
[[email protected]: only grab rcu lock when necessary, per Vlastimil]
Link: https://lkml.kernel.org/r/[email protected]
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Analysis
by VulDB Data Team • 09/29/2025
The vulnerability CVE-2024-43888 represents a use-after-free condition in the Linux kernel's memory management subsystem, specifically within the list_lru implementation that handles memory cgroup operations. This issue affects the mem_cgroup_from_slab_obj() function which is responsible for retrieving memory cgroup information from slab objects. The flaw occurs when the function is called without proper synchronization mechanisms to prevent the memory cgroup structure from being freed while the function is still accessing it, creating a scenario where stale memory references can lead to unpredictable behavior and potential security exploitation.
The technical root cause stems from insufficient locking mechanisms around the mem_cgroup_from_slab_obj() function call within the memory cgroup subsystem. The function is designed to be invoked under specific locking contexts such as RCU locks or cgroup_mutex to ensure that the returned memory cgroup structure remains valid throughout the function execution. However, in certain code paths, these protective mechanisms were omitted, leaving the function vulnerable to accessing memory that may have already been freed. This particular vulnerability was identified through code inspection rather than through exploitation, indicating the presence of a defensive programming error where proper synchronization was not consistently applied.
The operational impact of this vulnerability extends beyond simple memory corruption as it represents a potential vector for privilege escalation and system instability. When a use-after-free condition occurs in kernel space, attackers could potentially manipulate the freed memory to execute arbitrary code with kernel privileges, leading to complete system compromise. The vulnerability affects systems running Linux kernels where memory cgroup functionality is utilized, particularly those implementing memory resource management for containerized environments or virtualized workloads. The flaw's presence in the list_lru subsystem means that any process accessing memory cgroup information through slab objects could trigger the condition, making it a latent threat that may be exploited under specific memory pressure conditions.
The fix implemented addresses this vulnerability by adding the missing RCU read lock around the mem_cgroup_from_slab_obj() function call, ensuring proper synchronization with the memory cgroup lifecycle management. This solution aligns with established kernel programming practices for protecting data structures accessed under concurrent conditions, where RCU (Read-Copy-Update) mechanisms provide the necessary protection against use-after-free scenarios. The patch was developed following community feedback to optimize lock acquisition only when necessary, reducing performance overhead while maintaining security. This approach follows the principle of minimal locking required for correctness, as recommended in kernel development best practices and aligns with common security patterns described in the ATT&CK framework under system binary exploitation techniques. The fix directly addresses CWE-416, which covers use-after-free vulnerabilities, and represents a defensive programming correction that prevents improper memory access patterns in kernel space operations.