CVE-2022-48773 in Linux
Summary
by MITRE • 07/16/2024
In the Linux kernel, the following vulnerability has been resolved:
xprtrdma: fix pointer derefs in error cases of rpcrdma_ep_create
If there are failures then we must not leave the non-NULL pointers with the error value, otherwise `rpcrdma_ep_destroy` gets confused and tries free them, resulting in an Oops.
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Analysis
by VulDB Data Team • 10/28/2024
The vulnerability identified as CVE-2022-48773 resides within the Linux kernel's xprtrdma transport layer, specifically affecting the rpcrdma_ep_create function implementation. This issue represents a classic null pointer dereference scenario that occurs during error handling pathways within the RDMA (Remote Direct Memory Access) transport mechanism used for network communications in distributed systems. The vulnerability manifests when the kernel's RPC (Remote Procedure Call) subsystem attempts to establish RDMA endpoints for network operations, particularly in high-performance computing environments where direct memory access optimizations are critical for system performance.
The technical flaw stems from improper pointer management during error conditions within the xprtrdma subsystem. When the rpcrdma_ep_create function encounters failures during endpoint creation, it fails to properly initialize or clear pointers that may have been partially allocated or assigned during the setup process. This results in non-NULL pointers containing error values rather than valid memory references, creating a dangerous state where subsequent cleanup functions cannot properly distinguish between legitimate pointers requiring deallocation and error-indicating values. The root cause aligns with CWE-476, which addresses null pointer dereference vulnerabilities, and more specifically with CWE-825, which deals with attempts to access freed memory or improper pointer handling during error conditions.
The operational impact of this vulnerability is significant within environments utilizing RDMA-based networking, particularly in high-performance computing clusters, data centers, and distributed storage systems where the Linux kernel's RPC transport mechanisms are extensively deployed. When triggered, the vulnerability results in kernel oops conditions that cause system instability, potential crashes, and service disruptions. The error scenario typically occurs during network endpoint establishment failures, such as when insufficient resources are available, network configuration issues arise, or hardware communication problems occur. Systems running applications that rely on NFS (Network File System) or other RPC-based services using RDMA transport are particularly vulnerable, as these services frequently create and destroy RDMA endpoints during normal operations.
The mitigation strategy involves ensuring proper error handling and pointer management within the rpcrdma_ep_create function to prevent invalid pointer states during error conditions. This requires implementing robust cleanup procedures that properly initialize all pointers to NULL before attempting allocations, and ensuring that error paths explicitly clear or reset pointers that may have been partially assigned. The fix addresses the fundamental issue by ensuring that when errors occur, the system maintains consistent state management where pointers either contain valid references or are explicitly set to NULL, preventing the rpcrdma_ep_destroy function from attempting to free invalid memory references. This vulnerability demonstrates the critical importance of proper resource management and error handling in kernel space code, aligning with ATT&CK technique T1547.001 for privilege escalation through kernel exploits and highlighting the need for rigorous testing of error conditions in system-level components. Organizations should prioritize applying the kernel patches that resolve this vulnerability and implement monitoring for system instability or kernel oops messages that may indicate exploitation attempts or similar memory management issues in their RDMA-enabled environments.