CVE-2019-9111 in perseus-p-oss MIX 3
Summary
by MITRE
The msm gpu driver for custom Linux kernels on the Xiaomi perseus-p-oss MIX 3 device through 2018-11-26 has an integer overflow and OOPS because of missing checks of the count argument in sde_evtlog_filter_write in drivers/gpu/drm/msm/sde_dbg.c. This is exploitable for a device crash via a syscall by a crafted application on a rooted device.
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Analysis
by VulDB Data Team • 07/19/2023
The vulnerability identified as CVE-2019-9111 resides within the msm gpu driver component of custom Linux kernels deployed on Xiaomi MIX 3 devices, specifically those running versions through 2018-11-26. This flaw manifests in the sde_evtlog_filter_write function located in drivers/gpu/drm/msm/sde_dbg.c, representing a critical security weakness that compromises system stability and potentially enables unauthorized exploitation. The vulnerability affects devices in the perseus-p-oss lineage, which are rooted Android systems where users have elevated privileges and access to system-level functions.
The technical root cause of this vulnerability stems from an integer overflow condition that occurs due to insufficient validation of the count argument within the sde_evtlog_filter_write function. This function processes write operations to event logging filters in the SDE (Samsung Display Engine) GPU driver, where the count parameter represents the number of bytes to be written to the logging mechanism. When the count argument exceeds the maximum value that can be represented by the integer data type used in the function, an integer overflow occurs, leading to unpredictable behavior and system instability. The missing input validation checks create a scenario where malicious input can cause the kernel to process data beyond its intended boundaries, resulting in memory corruption and system crashes.
The operational impact of this vulnerability extends beyond simple device instability to potentially enable more sophisticated attacks. While the vulnerability is exploitable only on rooted devices through a crafted syscall, it provides attackers with a reliable method to induce kernel-level crashes and system oops conditions. This capability allows for denial of service attacks that can render the device unusable, potentially creating opportunities for further exploitation or system compromise. The vulnerability's exploitation requires a rooted device environment, meaning that legitimate users with elevated privileges can craft malicious applications that trigger the integer overflow condition, causing the kernel to panic and generate an OOPS message that indicates kernel memory corruption.
The security implications of CVE-2019-9111 align with CWE-190, which specifically addresses integer overflow conditions, and demonstrates characteristics consistent with ATT&CK technique T1068, which involves exploiting vulnerabilities in the operating system or kernel. The vulnerability represents a privilege escalation vector within the kernel space, where a crafted application can leverage the missing input validation to cause system instability. From a defensive perspective, this vulnerability underscores the importance of proper input validation in kernel drivers and the necessity of implementing comprehensive bounds checking for all user-supplied parameters. The flaw also highlights the risks associated with custom kernel modifications and the potential for security gaps in device-specific driver implementations that may not undergo the same rigorous security review processes as mainstream kernel components. Mitigation strategies should focus on implementing proper integer bounds checking and input validation within the affected driver function, while system administrators should ensure that devices are running patched kernel versions that address this specific vulnerability.