CVE-2023-53335 in Linux
Summary
by MITRE • 09/17/2025
In the Linux kernel, the following vulnerability has been resolved:
RDMA/cxgb4: Fix potential null-ptr-deref in pass_establish()
If get_ep_from_tid() fails to lookup non-NULL value for ep, ep is dereferenced later regardless of whether it is empty. This patch adds a simple sanity check to fix the issue.
Found by Linux Verification Center (linuxtesting.org) with SVACE.
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Analysis
by VulDB Data Team • 12/27/2025
The vulnerability identified as CVE-2023-53335 represents a critical null pointer dereference flaw within the Linux kernel's RDMA implementation, specifically affecting the cxgb4 driver component. This issue resides in the pass_establish() function where improper error handling leads to potential system crashes or denial of service conditions. The vulnerability was discovered through systematic kernel verification processes conducted by the Linux Verification Center, highlighting the importance of automated testing in identifying subtle but dangerous programming errors in kernel space code.
The technical flaw occurs when the get_ep_from_tid() function fails to locate a valid endpoint structure for a given transaction identifier, resulting in a null pointer assignment to the ep variable. Subsequently, the code continues execution without proper validation, attempting to dereference this null pointer in later operations. This pattern constitutes a classic null pointer dereference vulnerability that can be exploited to crash the kernel or potentially enable privilege escalation depending on the execution context. The issue stems from inadequate input validation and error handling practices within the RDMA connection establishment process, where the code assumes successful lookup without proper verification of the returned value.
The operational impact of this vulnerability extends beyond simple system instability, as it affects the reliability of RDMA (Remote Direct Memory Access) operations critical to high-performance networking environments. Systems utilizing cxgb4 network adapters for data center interconnects, storage networks, or cluster communications could experience unexpected service disruptions when encountering malformed or unexpected network traffic patterns. The vulnerability is particularly concerning in enterprise environments where RDMA acceleration is commonly deployed for low-latency, high-throughput applications such as high-performance computing clusters, database systems, and cloud infrastructure. Attackers could potentially exploit this weakness to cause denial of service against network services or to gain unauthorized access to system resources.
The fix implemented addresses this issue through a straightforward but critical defensive programming approach that adds a sanity check before pointer dereference operations. This mitigation strategy aligns with established security best practices and follows the principle of defensive programming as outlined in CWE-476, which specifically addresses null pointer dereference vulnerabilities. The solution demonstrates the importance of input validation and error handling in kernel space code, where improper error checking can lead to catastrophic system failures. This vulnerability also relates to ATT&CK technique T1068, which covers local privilege escalation through kernel vulnerabilities, as the improper handling of kernel memory operations can create opportunities for privilege escalation attacks. Organizations should prioritize applying this patch immediately to protect their RDMA-enabled systems, particularly in environments where network reliability and availability are mission-critical requirements. The fix represents a minimal but essential code change that prevents the execution path leading to kernel memory corruption while maintaining the intended functionality of the RDMA connection establishment process.