CVE-2024-49852 in Linux
Summary
by MITRE • 10/21/2024
In the Linux kernel, the following vulnerability has been resolved:
scsi: elx: libefc: Fix potential use after free in efc_nport_vport_del()
The kref_put() function will call nport->release if the refcount drops to zero. The nport->release release function is _efc_nport_free() which frees "nport". But then we dereference "nport" on the next line which is a use after free. Re-order these lines to avoid the use after free.
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Analysis
by VulDB Data Team • 01/19/2026
The vulnerability identified as CVE-2024-49852 represents a critical use after free condition within the Linux kernel's SCSI subsystem, specifically affecting the emulex efc (Emulex Fibre Channel) driver implementation. This flaw exists in the efc_nport_vport_del() function where improper handling of reference counting leads to memory safety violations. The issue manifests when the kref_put() function executes and decrements the reference count to zero, triggering the invocation of the nport->release callback function _efc_nport_free(). This release function subsequently frees the nport memory structure, yet the code continues to reference the freed memory location on the following line, creating a classic use after free scenario that can lead to arbitrary code execution or system instability.
The technical nature of this vulnerability aligns with CWE-416, which specifically addresses the use of memory after it has been freed, and represents a fundamental flaw in the reference counting mechanism within the kernel's SCSI driver framework. The flaw occurs in the context of Fibre Channel protocol handling where the emulex efc driver manages virtual port deletion operations. When a virtual port is being deleted, the driver fails to properly sequence the memory deallocation and subsequent memory access operations, violating fundamental memory safety principles that are essential for kernel-level software stability and security. This type of vulnerability falls under the ATT&CK technique T1068, which involves exploiting local privileges to execute malicious code through kernel-level memory corruption.
The operational impact of this vulnerability extends beyond simple memory corruption, as it can be exploited by malicious actors with local access to potentially escalate privileges or cause system crashes. The emulex efc driver handles Fibre Channel communication protocols that are commonly used in enterprise storage environments, making this vulnerability particularly concerning for data center and cloud infrastructure deployments. When exploited, the use after free condition could allow attackers to execute arbitrary code with kernel-level privileges, potentially leading to complete system compromise. The vulnerability affects systems running Linux kernels that include the emulex efc driver implementation, particularly those utilizing emulex Fibre Channel HBAs in storage area network configurations.
Mitigation strategies for CVE-2024-49852 require immediate kernel updates from vendors that address the specific memory management issue within the efc_nport_vport_del() function. System administrators should prioritize patching affected systems, particularly those running emulex Fibre Channel storage controllers, as the vulnerability can be exploited through local user access to trigger the memory corruption. The fix involves reordering the sequence of operations in the affected function to ensure that memory deallocation occurs before any subsequent references to the freed structure. Additionally, organizations should implement monitoring for unusual system behavior or kernel crashes that might indicate exploitation attempts, while maintaining proper access controls to limit local user privileges on systems handling sensitive storage infrastructure. The vulnerability demonstrates the critical importance of proper reference counting and memory management in kernel drivers, where even seemingly minor implementation errors can lead to severe security implications.