CVE-2019-19543 in Linux
Summary
by MITRE
In the Linux kernel before 5.1.6, there is a use-after-free in serial_ir_init_module() in drivers/media/rc/serial_ir.c.
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Analysis
by VulDB Data Team • 03/07/2024
The vulnerability identified as CVE-2019-19543 represents a critical use-after-free condition within the Linux kernel's remote control subsystem, specifically affecting versions prior to 5.1.6. This flaw exists in the serial_ir_init_module() function located in the drivers/media/rc/serial_ir.c file, which handles initialization of serial infrared remote control devices. The issue arises from improper memory management during the module initialization process, creating a scenario where freed memory locations may still be accessed or referenced by subsequent operations, potentially leading to arbitrary code execution or system instability.
The technical root cause of this vulnerability stems from a classic memory safety issue classified under CWE-416, which describes the use of freed memory condition. During the initialization of serial infrared remote control modules, the kernel code allocates memory for device structures and configuration data, but fails to properly manage the lifecycle of these allocations. When the module initialization process encounters certain error conditions or early termination scenarios, the allocated memory gets freed but references to this memory persist within the kernel's data structures or control flow paths. Subsequent operations that attempt to access this freed memory location can result in unpredictable behavior, including information disclosure, privilege escalation, or denial of service conditions.
The operational impact of CVE-2019-19543 extends beyond simple system stability concerns, as it can be exploited to achieve privilege escalation within the kernel context. Attackers with local access to systems running vulnerable kernel versions can leverage this use-after-free condition to execute arbitrary code with kernel-level privileges, effectively bypassing standard security boundaries. This vulnerability particularly affects systems that utilize serial infrared remote control functionality, including embedded devices, media centers, and various computing platforms that support infrared remote control interfaces. The exploitation potential is significant given that the flaw exists in core kernel functionality and can be triggered through normal device initialization sequences without requiring special privileges beyond basic user access.
Mitigation strategies for CVE-2019-19543 primarily focus on kernel version upgrades to 5.1.6 or later, which contain the necessary patches addressing the memory management issues in the serial infrared driver. System administrators should prioritize updating affected systems to the patched kernel versions while maintaining continuous monitoring for any signs of exploitation attempts. Additional defensive measures include implementing kernel module whitelisting policies, restricting device initialization access through proper privilege controls, and monitoring for anomalous kernel memory access patterns. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and kernel module manipulation, with potential lateral movement capabilities when exploited in environments with multiple affected systems. Organizations should also consider implementing runtime protections and memory integrity checks to detect and prevent exploitation attempts targeting similar memory safety vulnerabilities in their kernel environments.