CVE-2017-8257 in Android
Summary
by MITRE
In all Qualcomm products with Android releases from CAF using the Linux kernel, when accessing the sde_rotator debug interface for register reading with multiple processes, one process can free the debug buffer while another process still has the debug buffer in use.
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Analysis
by VulDB Data Team • 01/09/2021
The vulnerability identified as CVE-2017-8257 represents a critical race condition flaw within Qualcomm's Android implementations that leverages the Linux kernel's sde_rotator debug interface. This issue specifically affects devices where multiple processes attempt to access the same debug buffer simultaneously, creating a scenario where one process may prematurely release memory resources while another process continues to reference the same memory location. The root cause stems from inadequate synchronization mechanisms within the kernel driver that manages the sde_rotator hardware component, which is responsible for display rotation operations in Qualcomm's Snapdragon processors. This flaw exists across all Qualcomm products utilizing Android releases from the Code Aurora Forum that incorporate the Linux kernel, making it pervasive across numerous mobile devices and embedded systems. The vulnerability manifests when concurrent processes access the debug interface for register reading operations, exposing a fundamental flaw in resource management and memory deallocation protocols.
The technical exploitation of this vulnerability occurs through a classic race condition scenario where process scheduling and memory management intersect improperly. When multiple processes access the sde_rotator debug interface simultaneously, the kernel driver fails to properly coordinate access to shared memory buffers, leading to a situation where one process frees a debug buffer while another process maintains active references to it. This creates a use-after-free condition that can potentially allow malicious actors to execute arbitrary code or cause system instability. The flaw operates at the kernel level within the Qualcomm-specific driver implementation, making it particularly dangerous as it can affect system stability and potentially provide attack vectors for privilege escalation. The vulnerability is classified under CWE-362, which specifically addresses Race Conditions, and aligns with ATT&CK technique T1068, which covers Exploitation for Privilege Escalation through kernel-level vulnerabilities. The sde_rotator interface itself is part of Qualcomm's display subsystem, making this vulnerability particularly concerning as it can impact display functionality and potentially provide pathways for broader system compromise.
The operational impact of CVE-2017-8257 extends beyond simple system instability to potentially enable sophisticated attack scenarios that could compromise device security and user privacy. When exploited, this vulnerability could allow attackers to execute code with kernel privileges, effectively bypassing standard Android security boundaries and potentially providing access to sensitive user data, device credentials, or communication channels. The concurrent access nature of the flaw means that legitimate applications accessing the display subsystem could inadvertently trigger the race condition, leading to unpredictable behavior or system crashes. This vulnerability affects a broad range of devices including smartphones, tablets, and other mobile platforms that utilize Qualcomm Snapdragon processors, creating widespread exposure across the mobile ecosystem. The impact is particularly severe because the sde_rotator interface is commonly used for display-related operations, meaning that normal device functionality could be compromised, and the vulnerability could be triggered through routine operations rather than specifically crafted attacks.
Mitigation strategies for CVE-2017-8257 require both immediate patching and architectural improvements to prevent similar race conditions in kernel drivers. Qualcomm has released security updates and kernel patches addressing this specific vulnerability, which should be deployed immediately across affected devices. System administrators and device manufacturers should implement proper synchronization mechanisms within kernel drivers to prevent multiple processes from accessing shared resources simultaneously. The fix typically involves implementing proper locking mechanisms or reference counting to ensure that debug buffers remain allocated while any process is actively using them. Organizations should also consider implementing runtime monitoring to detect anomalous behavior that might indicate exploitation attempts. Additionally, security teams should review other kernel drivers for similar race condition vulnerabilities and apply defensive programming practices such as proper resource management, input validation, and access control mechanisms. The vulnerability serves as a reminder of the critical importance of secure kernel development practices and the need for comprehensive testing of concurrent access scenarios in embedded systems and mobile platforms.