CVE-2016-2546 in Android
Summary
by MITRE
sound/core/timer.c in the Linux kernel before 4.4.1 uses an incorrect type of mutex, which allows local users to cause a denial of service (race condition, use-after-free, and system crash) via a crafted ioctl call.
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Analysis
by VulDB Data Team • 09/12/2022
The vulnerability identified as CVE-2016-2546 resides within the Linux kernel's sound subsystem, specifically in the sound/core/timer.c file. This flaw represents a critical race condition issue that affects kernel versions prior to 4.4.1, creating a pathway for local attackers to exploit system stability through improper mutex handling. The vulnerability manifests when a crafted ioctl call is executed against the sound subsystem, potentially leading to system crashes and denial of service conditions that can severely impact system availability.
The technical root cause of this vulnerability stems from the incorrect usage of mutex types within the kernel's timer implementation. According to CWE-362, this represents a race condition vulnerability where concurrent access to shared resources occurs without proper synchronization mechanisms. The improper mutex implementation creates a scenario where memory structures can be freed while still being referenced by other kernel threads, resulting in use-after-free conditions that can be exploited to trigger system crashes. This type of vulnerability falls under the ATT&CK technique T1499.004 for Network Denial of Service and T1068 for Exploitation for Privilege Escalation.
The operational impact of this vulnerability extends beyond simple denial of service, as local users with minimal privileges can leverage this flaw to compromise system stability. The race condition allows for unpredictable behavior where kernel memory management becomes corrupted, potentially leading to kernel panics and system reboots. Attackers can repeatedly trigger the vulnerability to maintain persistent denial of service conditions, making it particularly dangerous in environments where system uptime is critical. The vulnerability's exploitation requires local access but does not necessitate elevated privileges, making it a significant concern for multi-user systems where untrusted users might have access to audio subsystem interfaces.
Mitigation strategies for CVE-2016-2546 primarily focus on kernel version updates, as the issue has been resolved in Linux kernel version 4.4.1 and subsequent releases. System administrators should prioritize patching affected systems and implementing proper kernel hardening measures. Additional protective measures include restricting access to audio subsystem interfaces through proper file permissions and monitoring for suspicious ioctl activity. The vulnerability demonstrates the importance of proper synchronization primitives in kernel development and highlights the need for thorough code review processes to prevent similar race condition issues in critical system components. Organizations should also implement continuous monitoring for kernel-level anomalies and maintain up-to-date security patches to protect against similar vulnerabilities in the sound subsystem and other kernel components.