CVE-2022-49199 in Linux
Summary
by MITRE • 02/26/2025
In the Linux kernel, the following vulnerability has been resolved:
RDMA/nldev: Prevent underflow in nldev_stat_set_counter_dynamic_doit()
This code checks "index" for an upper bound but it does not check for negatives. Change the type to unsigned to prevent underflows.
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Analysis
by VulDB Data Team • 10/21/2025
The vulnerability identified as CVE-2022-49199 resides within the Linux kernel's RDMA (Remote Direct Memory Access) subsystem, specifically in the nldev (netlink device) component that handles network device management through netlink sockets. This flaw manifests in the nldev_stat_set_counter_dynamic_doit() function which is responsible for setting dynamic counters within RDMA network devices. The vulnerability represents a classic integer underflow condition that can occur when processing device statistics through netlink communication interfaces. The issue stems from insufficient input validation where the function validates upper bounds for an index parameter but fails to check for negative values, creating a potential exploitation vector for malicious actors seeking to manipulate kernel memory structures.
The technical implementation of this vulnerability involves a type casting error where a signed integer variable is used to store an index value that should logically be non-negative. When an attacker provides a negative index value through the nldev_stat_set_counter_dynamic_doit() function, the lack of negative value validation allows the signed integer to underflow, potentially causing unpredictable behavior in kernel memory management. This type of vulnerability falls under the CWE-191 category of Integer Underflow (Wrap or Wraparound) and represents a fundamental flaw in input validation and data type handling within kernel space operations. The vulnerability is particularly concerning because it occurs in a kernel subsystem that handles low-level network device operations, making it accessible through legitimate netlink communication channels used by system administrators and network management tools.
The operational impact of CVE-2022-49199 extends beyond simple memory corruption, as it can potentially enable privilege escalation or denial of service conditions within systems utilizing RDMA networking capabilities. Attackers could exploit this vulnerability by sending specially crafted netlink messages containing negative index values to the nldev subsystem, which could result in memory corruption, system crashes, or potentially allow malicious code execution in kernel space. Systems running Linux kernels with RDMA support and active netlink communication interfaces are at risk, particularly those managing high-performance networking equipment, data center infrastructure, or systems with RDMA-enabled network adapters. The vulnerability aligns with ATT&CK technique T1068 which involves the exploitation of legitimate system tools and interfaces to gain elevated privileges or cause system instability.
Mitigation strategies for this vulnerability primarily involve updating to kernel versions that have patched the integer underflow issue by changing the index parameter type from signed to unsigned integer. The fix implemented in the patched kernel versions ensures that negative values cannot be processed by the nldev_stat_set_counter_dynamic_doit() function, thereby preventing the underflow condition. System administrators should prioritize applying the relevant kernel updates as soon as possible, particularly in environments where RDMA networking is actively used. Additional monitoring should be implemented to detect unusual netlink traffic patterns that might indicate exploitation attempts, and access controls should be enforced to limit who can send netlink messages to the affected subsystem. Organizations using RDMA technologies should also consider implementing network segmentation and privilege separation to minimize potential impact if exploitation were to occur. The vulnerability demonstrates the critical importance of proper input validation in kernel space code and highlights the need for comprehensive testing of boundary conditions in system-level programming.