CVE-2019-19072 in Linux
Summary
by MITRE
A memory leak in the predicate_parse() function in kernel/trace/trace_events_filter.c in the Linux kernel through 5.3.11 allows attackers to cause a denial of service (memory consumption), aka CID-96c5c6e6a5b6.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 02/23/2024
The vulnerability identified as CVE-2019-19072 represents a critical memory management flaw within the Linux kernel's tracing subsystem that specifically affects versions through 5.3.11. This issue resides in the predicate_parse() function located within kernel/trace/trace_events_filter.c, which is responsible for parsing filter predicates used in kernel trace events. The memory leak occurs during the processing of trace event filters, where allocated memory structures are not properly released when certain parsing conditions are met, leading to gradual memory exhaustion over time.
The technical implementation of this vulnerability stems from inadequate memory deallocation practices within the kernel's trace filtering mechanism. When an attacker crafts malicious trace filter predicates that trigger specific parsing paths in the predicate_parse() function, the system fails to release previously allocated memory blocks, causing a progressive accumulation of unreleased memory. This memory leak directly correlates with the trace events filtering subsystem, which is commonly used for debugging and monitoring kernel activities, making it accessible through various legitimate kernel interfaces. The vulnerability manifests as a gradual increase in memory consumption that can eventually lead to system instability or complete denial of service when system resources are exhausted.
The operational impact of this vulnerability extends beyond simple resource exhaustion, as it can be exploited by unprivileged users to systematically consume system memory and cause service disruption. Attackers can repeatedly trigger the memory leak by submitting crafted trace filter expressions through the /sys/kernel/debug/tracing/trace_events/ interface or related kernel debugging mechanisms. This allows for sustained memory consumption that can degrade system performance or cause complete system hangs, particularly on systems with limited memory resources. The vulnerability affects systems running Linux kernel versions up to 5.3.11, making it relevant for a substantial portion of deployed kernel versions that were widely used in enterprise and embedded environments.
Mitigation strategies for CVE-2019-19072 should focus on immediate kernel updates to versions 5.4 or later where the memory leak has been addressed through proper memory management practices. System administrators should also implement monitoring solutions to detect unusual memory consumption patterns in kernel trace subsystems, particularly around the trace_events_filter.c module. The fix implemented in patched versions typically involves ensuring that all allocated memory structures within the predicate_parse() function are properly freed regardless of parsing outcomes, preventing the accumulation of unreleased memory blocks. Organizations should also consider restricting access to kernel debugging interfaces and implementing resource limits on trace event filtering operations to minimize potential exploitation impact. This vulnerability aligns with CWE-401 Memory Leak and can be categorized under ATT&CK technique T1499.002 for resource exhaustion attacks, representing a significant concern for system availability in kernel-level security contexts.
The vulnerability demonstrates the critical importance of proper memory management in kernel space operations and highlights how seemingly benign filtering mechanisms can become attack vectors when memory cleanup is inadequate. This flaw underscores the necessity of thorough code review processes for kernel subsystems that handle user-provided data, particularly those involving parsing and filtering operations that may be subject to malicious input. The memory leak pattern observed in this vulnerability reflects common pitfalls in kernel development where resource cleanup is not properly handled during error conditions or exceptional processing paths, making it a valuable case study for understanding kernel security best practices and the importance of comprehensive testing for memory management in operating system components.