CVE-2022-0812 Overview
An information leak vulnerability was discovered in the Linux Kernel's NFS over RDMA implementation, specifically within the net/sunrpc/xprtrdma/rpc_rdma.c component. This flaw allows an attacker with normal user privileges to potentially leak sensitive kernel information through the Remote Direct Memory Access (RDMA) transport layer used for NFS operations.
Critical Impact
Authenticated users with low-privilege access can exploit this vulnerability to extract kernel memory contents, potentially exposing sensitive data including kernel addresses, cryptographic keys, or other confidential information useful for further attacks.
Affected Products
- Linux Kernel (multiple versions)
- Linux Kernel 5.8.0-rc1 through 5.8.0-rc5
- Systems utilizing NFS over RDMA transport
Discovery Timeline
- August 29, 2022 - CVE-2022-0812 published to NVD
- November 21, 2024 - Last updated in NVD database
Technical Details for CVE-2022-0812
Vulnerability Analysis
This vulnerability represents an information disclosure weakness in the Linux Kernel's Sun RPC RDMA transport implementation for NFS. The flaw resides in the rpc_rdma.c file, which handles the RDMA-based transport protocol for NFS operations. When processing certain NFS over RDMA requests, the kernel fails to properly sanitize memory contents before transmitting data, resulting in unintended exposure of kernel memory to user-space applications.
The information leak can be triggered by authenticated users with standard privileges, making it accessible to any local user account on affected systems. While the vulnerability does not directly enable code execution or privilege escalation, the leaked kernel information could assist attackers in bypassing security mechanisms such as Kernel Address Space Layout Randomization (KASLR) or in crafting more sophisticated exploits.
Root Cause
The root cause of CVE-2022-0812 stems from improper memory handling in the NFS over RDMA subsystem. Specifically, the code in net/sunrpc/xprtrdma/rpc_rdma.c fails to properly initialize or clear memory buffers before they are transmitted via RDMA operations. This results in uninitialized memory contents—potentially containing sensitive kernel data—being exposed to authenticated users through the NFS RDMA transport layer.
Attack Vector
The attack can be executed over the network by any authenticated user with low privileges. The exploitation requires:
- Network access to a system with NFS over RDMA enabled
- Valid user credentials (low privilege sufficient)
- Ability to initiate NFS operations over the RDMA transport
The attacker initiates specific NFS operations that trigger the vulnerable code path, causing the kernel to expose memory contents through improperly sanitized RDMA responses. The leaked information is returned to the attacker without requiring user interaction.
The vulnerability has been addressed in the Linux kernel through commit 912288442cb2f431bf3c8cb097a5de83bc6dbac1, which properly sanitizes memory buffers before transmission. See the Linux Kernel Commit Update for technical implementation details.
Detection Methods for CVE-2022-0812
Indicators of Compromise
- Unusual NFS over RDMA traffic patterns or excessive NFS mount operations
- Unexpected memory read operations from the xprtrdma kernel module
- Anomalous user activity involving NFS mounts on RDMA-enabled storage systems
- Evidence of kernel memory contents in captured network traffic
Detection Strategies
- Monitor kernel logs for warnings or errors related to the xprtrdma module and rpc_rdma.c operations
- Deploy network monitoring to identify unusual NFS over RDMA traffic patterns
- Implement file integrity monitoring on NFS-mounted resources
- Use kernel auditing to track operations involving the Sun RPC RDMA subsystem
Monitoring Recommendations
- Enable detailed logging for NFS and RDMA-related kernel modules
- Monitor for unauthorized access attempts to NFS-mounted file systems
- Implement alerting for unusual kernel memory access patterns
- Review authentication logs for unexpected user activity on NFS-enabled systems
How to Mitigate CVE-2022-0812
Immediate Actions Required
- Apply the latest Linux kernel security updates containing the fix (commit 912288442cb2f431bf3c8cb097a5de83bc6dbac1)
- Review and restrict user access to NFS over RDMA resources
- Consider disabling NFS over RDMA if not required for business operations
- Implement network segmentation to limit exposure of RDMA-enabled NFS services
Patch Information
The vulnerability has been addressed in upstream Linux kernel commits. Organizations should update to patched kernel versions as provided by their distribution vendors. Multiple vendors have released advisories and patches:
- Red Hat CVE Advisory - Contains Red Hat-specific patching guidance
- Ubuntu CVE Advisory - Ubuntu security update information
- NetApp Security Advisory - NetApp product impact and patches
The fix is available in the mainline Linux kernel via the Linux Kernel Commit Update.
Workarounds
- Disable NFS over RDMA transport if not essential to operations
- Restrict network access to NFS services using firewall rules
- Limit user accounts with access to NFS-mounted resources
- Enable strict authentication requirements for NFS operations
# Disable NFS over RDMA module (temporary workaround)
modprobe -r xprtrdma
echo "blacklist xprtrdma" >> /etc/modprobe.d/blacklist-xprtrdma.conf
# Restrict NFS access via firewall
iptables -A INPUT -p tcp --dport 2049 -j DROP
iptables -A INPUT -p tcp --dport 2049 -s trusted_network/24 -j ACCEPT
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
