CVE-2018-11265 in Android
Summary
by MITRE
In all android releases(Android for MSM, Firefox OS for MSM, QRD Android) from CAF using the linux kernel, possible buffer overflow while incrementing the log_buf of type uint64_t in memcpy function, since the log_buf pointer can access the memory beyond the size to store the data after pointer increment.
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Analysis
by VulDB Data Team • 05/16/2023
This vulnerability exists in android kernel implementations across multiple platforms including MSM devices, Firefox OS for MSM, and QRD Android systems. The issue stems from improper boundary checking during buffer management operations within the kernel logging subsystem. The flaw manifests when the log_buf pointer is incremented during memory copy operations, creating a potential buffer overflow condition that can lead to memory corruption and system instability. The vulnerability specifically affects the memcpy function where the uint64_t type log_buf pointer can access memory locations beyond the intended buffer boundaries, creating an exploitable condition that violates fundamental memory safety principles.
The technical implementation of this vulnerability involves the kernel's logging mechanism where the log_buf pointer is incremented without adequate validation of the resulting memory access bounds. This creates a classic buffer overflow scenario where the pointer arithmetic can cause the system to write data beyond the allocated buffer space, potentially overwriting adjacent memory regions. The uint64_t type specification does not provide any inherent protection against this overflow condition, as the increment operation can still result in pointer values that exceed the valid memory allocation limits. This vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios, though the specific implementation here involves kernel memory management rather than user-space buffers.
The operational impact of this vulnerability extends beyond simple memory corruption to potentially enable privilege escalation and system compromise. An attacker who can control the logging operations or manipulate the buffer increment logic could potentially exploit this condition to execute arbitrary code within kernel space, leading to full system compromise. The vulnerability affects the core kernel functionality that handles system logging, making it particularly dangerous as it operates at the lowest privilege level where system integrity is maintained. This condition could allow malicious actors to bypass security controls, modify critical system data, or establish persistent backdoors within the kernel execution environment.
Mitigation strategies for this vulnerability should focus on implementing proper bounds checking mechanisms within the kernel logging subsystem. The most effective approach involves adding validation checks before pointer increment operations to ensure that memory access remains within allocated buffer boundaries. Kernel developers should implement proper input validation and boundary checking within the memcpy operations that handle log_buf management, preventing the pointer from accessing memory beyond the intended buffer limits. Additionally, implementing memory protection mechanisms such as stack canaries, address space layout randomization, and kernel address space layout randomization can help mitigate exploitation attempts. The fix should align with the principle of least privilege and defensive programming practices, ensuring that all kernel memory operations include proper validation before any pointer arithmetic or memory access operations occur. This vulnerability demonstrates the critical importance of proper kernel memory management and highlights the need for comprehensive security testing of kernel subsystems.