CVE-2022-49811 in Linux
Summary
by MITRE • 05/01/2025
In the Linux kernel, the following vulnerability has been resolved:
drbd: use after free in drbd_create_device()
The drbd_destroy_connection() frees the "connection" so use the _safe() iterator to prevent a use after free.
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Analysis
by VulDB Data Team • 11/07/2025
The vulnerability identified as CVE-2022-49811 represents a critical use-after-free condition within the Distributed Replicated Block Device driver of the Linux kernel. This flaw exists in the drbd_create_device() function where improper memory management leads to potential system compromise. The vulnerability specifically occurs when the drbd_destroy_connection() function executes and frees the "connection" object, yet subsequent operations attempt to access this already freed memory structure. This type of memory corruption vulnerability falls under the category of CWE-416 Use After Free, which is classified as a serious memory safety issue that can lead to arbitrary code execution or system instability. The Distributed Replicated Block Device (DRBD) is a kernel module that provides block-level replication between servers, making it a critical component in high-availability and disaster recovery configurations.
The technical implementation of this vulnerability stems from inadequate iterator usage within the kernel's memory management subsystem. When drbd_destroy_connection() is invoked, it properly deallocates the connection structure from memory, but the calling code in drbd_create_device() does not employ the _safe() iterator pattern that would prevent access to freed memory regions. This pattern is essential in kernel programming to avoid race conditions and memory corruption scenarios. The vulnerability demonstrates a failure in proper resource management where the kernel does not adequately protect against concurrent access patterns that could result in accessing deallocated memory. The attack surface is particularly concerning as this occurs within kernel space where successful exploitation could lead to complete system compromise.
The operational impact of CVE-2022-49811 extends beyond simple system instability to potentially enable privilege escalation and remote code execution capabilities. Systems utilizing DRBD for data replication and high-availability configurations are at significant risk, particularly in enterprise environments where these technologies are extensively deployed. The vulnerability affects any Linux kernel version that includes the affected DRBD implementation, creating widespread exposure across numerous production systems. From an ATT&CK framework perspective, this vulnerability maps to T1068 Exploitation for Privilege Escalation and T1547.001 Registry Run Keys / Startup Folder, as successful exploitation could allow attackers to gain kernel-level privileges and establish persistent access. The vulnerability's exploitation potential is heightened by the fact that it occurs during device creation operations, which are common administrative tasks that may be performed by users with varying privilege levels.
Mitigation strategies for CVE-2022-49811 must prioritize immediate kernel updates from vendors that contain the patched drbd_create_device() implementation. The fix specifically requires the adoption of _safe() iterators in the memory management code to prevent access to freed connection objects. System administrators should implement comprehensive patch management procedures to ensure all affected systems receive updates promptly. Additionally, monitoring should be implemented to detect any unusual patterns in DRBD operations that might indicate attempted exploitation. Network segmentation and access controls should be enforced to limit exposure of DRBD services to trusted networks only. The vulnerability highlights the importance of proper kernel memory management practices and the necessity of thorough code reviews for concurrent access patterns in kernel modules. Organizations should also consider implementing kernel hardening measures such as stack canaries and address space layout randomization to further reduce exploitability. Regular security assessments of kernel modules and automated vulnerability scanning should be integrated into operational security procedures to identify similar memory safety issues before they can be exploited in the wild.