CVE-2017-9677 in Android
Summary
by MITRE
In all Qualcomm products with Android releases from CAF using the Linux kernel, in function msm_compr_ioctl_shared, variable "ddp->params_length" could be accessed and modified by multiple threads, while it is not protected with locks. If one thread is running, while another thread is setting data, race conditions will happen. If "ddp->params_length" is set to a big number, a buffer overflow will occur.
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Analysis
by VulDB Data Team • 01/14/2021
The vulnerability identified as CVE-2017-9677 represents a critical race condition flaw within Qualcomm's Android-based products that utilize the Linux kernel. This issue manifests specifically within the msm_compr_ioctl_shared function where the variable ddp->params_length undergoes concurrent access without proper synchronization mechanisms. The flaw exists across all Qualcomm products that incorporate Android releases from the Code Aurora Forum and leverage the Linux kernel for their operational framework. The absence of thread locking mechanisms creates an environment where multiple threads can simultaneously access and modify the same memory location, fundamentally compromising the system's integrity and security posture.
The technical implementation of this vulnerability stems from inadequate concurrency control measures within the kernel-level audio processing subsystem. When multiple threads attempt to access ddp->params_length concurrently, the lack of proper mutex or spinlock protection allows for unpredictable execution flows where one thread may be reading while another is writing to the same memory location. This race condition creates a scenario where the data integrity of the parameter length field becomes compromised, leading to potential memory corruption issues. The vulnerability is particularly dangerous because it allows for arbitrary modification of the params_length variable, which directly influences buffer allocation decisions within the audio processing pipeline.
The operational impact of this vulnerability extends beyond simple memory corruption to encompass potential system instability and security compromise. When a malicious actor manipulates the ddp->params_length variable to an excessively large value, the system attempts to allocate an oversized buffer, resulting in a classic buffer overflow condition. This overflow can potentially be exploited to execute arbitrary code within the kernel space, providing attackers with elevated privileges and complete system control. The vulnerability affects the entire Qualcomm product ecosystem that relies on Android and the Linux kernel, making it a widespread concern across mobile devices, tablets, and other embedded systems. The exploitation of this flaw could lead to persistent backdoor access, data exfiltration, and complete device compromise, with implications for both individual user privacy and enterprise security infrastructure.
Mitigation strategies for CVE-2017-9677 require immediate implementation of proper locking mechanisms within the msm_compr_ioctl_shared function to ensure exclusive access to the ddp->params_length variable during read and write operations. The solution involves implementing mutex or spinlock protection around critical sections where the parameter length is accessed or modified, preventing concurrent thread interference. Additionally, input validation should be enforced to limit the maximum value that ddp->params_length can assume, preventing buffer overflow conditions even if race conditions occur. System administrators should prioritize firmware updates from Qualcomm and device manufacturers, as the fix requires kernel-level modifications that cannot be addressed through user-space patches. This vulnerability aligns with CWE-362, which specifically addresses race conditions, and represents a significant concern from an ATT&CK framework perspective under the T1059.006 technique for command and script injection, as successful exploitation could enable persistent access to system resources and facilitate further attack vectors.