CVE-2015-7885 in Linux
Summary
by MITRE
The dgnc_mgmt_ioctl function in drivers/staging/dgnc/dgnc_mgmt.c in the Linux kernel through 4.3.3 does not initialize a certain structure member, which allows local users to obtain sensitive information from kernel memory via a crafted application.
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Analysis
by VulDB Data Team • 06/23/2022
The vulnerability identified as CVE-2015-7885 resides within the Linux kernel's dgnc driver implementation, specifically in the dgnc_mgmt_ioctl function located at drivers/staging/dgnc/dgnc_mgmt.c. This flaw affects kernel versions through 4.3.3 and represents a classic information disclosure vulnerability that arises from improper initialization of kernel data structures. The issue manifests when a local user executes a crafted application that invokes the ioctl interface with specific parameters, leading to the exposure of sensitive data that should remain confidential within kernel memory space.
The technical root cause of this vulnerability stems from a failure to properly initialize a structure member within the dgnc_mgmt_ioctl function. According to CWE-457, this represents a use of uninitialized variable vulnerability where the kernel code does not adequately prepare memory before exposing it to user-space applications. When the ioctl function processes the crafted input, it fails to initialize certain fields of a data structure that subsequently gets copied to user space, creating a situation where uninitialized kernel memory contents are inadvertently revealed to the requesting process. This uninitialized memory may contain remnants of previous operations, sensitive kernel data, or other confidential information that should never be accessible to unprivileged users.
The operational impact of CVE-2015-7885 is significant for local attackers who can leverage this vulnerability to perform information gathering activities that may aid in further exploitation attempts. While the vulnerability does not directly enable privilege escalation or remote code execution, it provides attackers with valuable insights into kernel memory layout and internal state information that can be used to craft more sophisticated attacks. The exposure of kernel memory contents can reveal memory addresses, internal data structures, and potentially sensitive configuration information that would normally remain hidden from user-space processes. This information disclosure capability aligns with ATT&CK technique T1005, which covers data from local system, and can serve as a foundational step in broader exploitation campaigns.
The vulnerability demonstrates a critical flaw in kernel development practices regarding proper memory initialization and security-conscious coding standards. Modern secure coding guidelines emphasize that all variables and data structures must be properly initialized before use, particularly in kernel space where memory access controls are more relaxed. The issue highlights the importance of following established security frameworks and conducting thorough code reviews to identify potential information disclosure paths. Organizations should implement comprehensive patch management programs to address this vulnerability promptly, as the kernel version 4.3.3 and earlier releases are no longer supported and contain multiple security weaknesses that compound the risk profile. Mitigation strategies include applying the official kernel patches, implementing kernel lockdown mechanisms, and conducting regular security assessments of kernel modules to identify similar uninitialized variable issues that may exist in other subsystems.