CVE-2019-12380 in Linux
Summary
by MITRE
An issue was discovered in the efi subsystem in the Linux kernel through 5.1.5. phys_efi_set_virtual_address_map in arch/x86/platform/efi/efi.c and efi_call_phys_prolog in arch/x86/platform/efi/efi_64.c mishandle memory allocation failures.
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Analysis
by VulDB Data Team • 09/24/2023
The vulnerability identified as CVE-2019-12380 resides within the efi subsystem of the Linux kernel, affecting versions through 5.1.5 and representing a critical memory management flaw that can lead to system instability and potential privilege escalation. This issue manifests in two key functions within the x86 platform EFI implementation where the kernel fails to properly handle memory allocation failures during virtual address mapping operations. The problem specifically impacts the phys_efi_set_virtual_address_map function located in arch/x86/platform/efi/efi.c and the efi_call_phys_prolog function found in arch/x86/platform/efi/efi_64.c, both of which are integral components of the kernel's EFI runtime services handling mechanism.
The technical flaw stems from inadequate error checking during memory allocation operations within these EFI subsystem functions, creating a scenario where the kernel continues execution even when critical memory allocation requests fail. This failure to properly validate allocation outcomes can result in NULL pointer dereferences or memory corruption conditions that fundamentally compromise the kernel's stability. The vulnerability operates at the intersection of kernel memory management and EFI runtime services, where the system attempts to transition from physical to virtual memory mapping during EFI runtime operations, making it particularly dangerous as it can occur during critical system initialization or shutdown sequences. According to CWE classification, this vulnerability maps to CWE-704 as it involves improper handling of memory allocation failures, and potentially CWE-248 as it relates to an unspecified state in the kernel's EFI subsystem.
The operational impact of CVE-2019-12380 extends beyond simple system crashes to potentially enable privilege escalation attacks and denial of service conditions that can affect the entire system's boot process and runtime functionality. When memory allocation fails during EFI virtual address mapping, the system may experience unexpected behavior ranging from complete system hangs to more subtle corruption that could allow malicious actors to exploit the instability for privilege escalation. The vulnerability affects systems that rely on EFI runtime services for boot processes, secure boot implementations, and virtualization environments where EFI memory management is critical. Attackers could potentially leverage this flaw to cause system crashes, disrupt boot sequences, or in more sophisticated scenarios, exploit the memory corruption to gain elevated privileges within the kernel space, making it particularly concerning for enterprise environments and security-critical systems.
Mitigation strategies for CVE-2019-12380 should prioritize immediate kernel updates to versions that contain the patched implementations of the affected EFI subsystem functions. System administrators should ensure all affected systems are updated to kernel versions 5.2 or later where the memory allocation failure handling has been properly addressed. Additional defensive measures include implementing proper memory monitoring and allocation validation routines within custom kernel modules, though this approach is less recommended due to the complexity and potential for introducing new vulnerabilities. The ATT&CK framework categorizes this vulnerability under T1068 as it involves privilege escalation through kernel vulnerabilities, and T1499 for potential system disruption through denial of service conditions. Organizations should also consider implementing runtime monitoring to detect abnormal memory allocation patterns and system instability that could indicate exploitation attempts, while maintaining regular kernel patching schedules to prevent similar vulnerabilities from being exploited in the future.