CVE-2022-48844 in Linux
Summary
by MITRE • 07/16/2024
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: hci_core: Fix leaking sent_cmd skb
sent_cmd memory is not freed before freeing hci_dev causing it to leak it contents.
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Analysis
by VulDB Data Team • 10/11/2024
The vulnerability identified as CVE-2022-48844 represents a memory leak issue within the Linux kernel's Bluetooth subsystem, specifically affecting the hci_core module responsible for handling Bluetooth hardware communication. This flaw occurs during the cleanup process of Bluetooth device structures when the kernel attempts to free memory associated with a Bluetooth device but fails to properly release previously allocated socket buffer (skb) structures that were used for command transmission. The issue stems from improper memory management practices where the sent_cmd reference count is not decremented or freed before the hci_dev structure itself is destroyed, leading to a gradual accumulation of unreleased memory within the kernel's memory pool.
The technical root cause of this vulnerability can be categorized under CWE-401, which specifically addresses Improper Release of Memory Before Removing Last Reference. The flaw manifests when the Bluetooth subsystem receives a command to free a Bluetooth device structure, but the implementation does not properly iterate through and release all associated memory allocations including the sent_cmd skb structures that were used for previous command transmissions. This memory leak occurs in the context of the HCI (Host Controller Interface) core layer which manages the communication between the host system and Bluetooth hardware controllers, making it a critical issue for systems relying on Bluetooth connectivity.
The operational impact of this vulnerability extends beyond simple memory consumption issues, as it can lead to progressive system degradation and potential service disruption over time. When the kernel continuously leaks memory due to unreleased skb structures, it reduces the available memory for other system processes and can eventually contribute to system instability or performance degradation. In embedded systems or devices with limited memory resources, this memory leak could accelerate system resource exhaustion and potentially cause unexpected device failures or crashes. The vulnerability affects any Linux system running kernel versions prior to the fix, particularly those with Bluetooth functionality enabled and actively used.
Mitigation strategies for CVE-2022-48844 primarily involve applying the kernel patch that properly implements the cleanup of sent_cmd skb structures before freeing the hci_dev structure. System administrators should prioritize updating to kernel versions that include the fix, typically found in kernel releases 5.19 and later. The fix follows established security practices outlined in the ATT&CK framework under T1070.004, which addresses Indicator Removal on Host by ensuring proper resource cleanup. Additionally, organizations should implement monitoring solutions to track memory usage patterns and detect potential memory leaks in their Bluetooth-enabled systems. Regular kernel updates and vulnerability assessments should be part of the security maintenance routine to prevent similar issues from accumulating and potentially being exploited by adversaries seeking to cause system instability or resource exhaustion attacks.