CVE-2024-50262 in Linux
Summary
by MITRE • 11/09/2024
In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix out-of-bounds write in trie_get_next_key()
trie_get_next_key() allocates a node stack with size trie->max_prefixlen, while it writes (trie->max_prefixlen + 1) nodes to the stack when it has full paths from the root to leaves. For example, consider a trie with max_prefixlen is 8, and the nodes with key 0x00/0, 0x00/1, 0x00/2, ... 0x00/8 inserted. Subsequent calls to trie_get_next_key with _key with .prefixlen = 8 make 9 nodes be written on the node stack with size 8.
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Analysis
by VulDB Data Team • 07/16/2025
The vulnerability identified as CVE-2024-50262 represents a critical out-of-bounds write condition within the Linux kernel's BPF (Berkeley Packet Filter) subsystem, specifically affecting the trie_get_next_key() function. This flaw exists in the trie data structure implementation used for efficient prefix matching operations within the kernel's networking and security frameworks. The issue stems from a fundamental mismatch between allocated memory space and actual write operations, creating a potential avenue for arbitrary code execution or system instability. The vulnerability manifests when processing trie data structures that store network prefixes, particularly impacting systems utilizing BPF programs for packet filtering, traffic control, or security monitoring functions. This type of out-of-bounds write vulnerability directly aligns with CWE-121, which describes unsafe array access conditions that can lead to memory corruption and potentially privilege escalation.
The technical implementation flaw occurs due to improper memory allocation sizing within the trie_get_next_key() function where the node stack is allocated with a size equal to trie->max_prefixlen. However, the function subsequently writes (trie->max_prefixlen + 1) nodes to this stack during operations involving full paths from root to leaf nodes in the trie structure. This discrepancy becomes particularly problematic when dealing with trie configurations where the maximum prefix length is set to values such as 8, and the trie contains nodes with keys spanning the complete prefix range from 0x00/0 through 0x00/8. When subsequent calls to trie_get_next_key() process keys with _key.prefixlen = 8, the function attempts to write 9 nodes onto a stack that was only allocated for 8 nodes, resulting in the overflow condition. The flaw demonstrates a classic buffer overflow pattern where the allocated buffer size calculation does not account for the maximum possible number of nodes that may be traversed during the path expansion process.
The operational impact of this vulnerability extends beyond simple memory corruption, potentially enabling attackers to execute arbitrary code with kernel privileges or cause system crashes through controlled memory writes. Systems running Linux kernels with BPF functionality, particularly those implementing traffic control, packet filtering, or network monitoring through BPF programs, are at risk. The vulnerability is especially concerning in environments where untrusted users can submit BPF programs or where BPF programs interact with user-controlled data, as this could enable privilege escalation attacks. The flaw affects the kernel's trie data structure implementation, which is fundamental to many networking operations and security features, making it a critical issue for system administrators and security professionals. According to ATT&CK framework category T1068, this vulnerability could be exploited for privilege escalation, while T1595 covers the initial access vectors that might leverage such kernel-level flaws. The potential for denial of service attacks is significant, as the out-of-bounds write can corrupt kernel memory structures and lead to system panics or reboots, particularly in high-traffic network environments.
Mitigation strategies for CVE-2024-50262 should focus on immediate kernel updates from vendors such as Red Hat, SUSE, Ubuntu, and other Linux distributions, as patches addressing this specific out-of-bounds write condition have been developed and released. System administrators should prioritize patching all affected kernel versions, particularly in production environments running BPF programs or network security functions. Additional defensive measures include implementing proper BPF program validation and sandboxing mechanisms to limit potential exploitation vectors, monitoring for suspicious BPF program loading activities, and restricting user access to BPF-related system calls where possible. The vulnerability highlights the importance of thorough memory management reviews in kernel subsystems and underscores the necessity of rigorous testing for edge cases in data structure implementations. Organizations should also consider implementing network segmentation and monitoring to detect potential exploitation attempts targeting kernel-level vulnerabilities, as the out-of-bounds write could be leveraged for more sophisticated attacks including privilege escalation or persistent backdoor installation. Security teams should conduct comprehensive vulnerability assessments to identify systems running affected kernel versions and ensure proper patch management procedures are in place to prevent similar issues in other kernel subsystems.