CVE-2011-1476 in Linux
Summary
by MITRE
Integer underflow in the Open Sound System (OSS) subsystem in the Linux kernel before 2.6.39 on unspecified non-x86 platforms allows local users to cause a denial of service (memory corruption) by leveraging write access to /dev/sequencer.
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Analysis
by VulDB Data Team • 12/05/2021
The vulnerability identified as CVE-2011-1476 represents a critical integer underflow condition within the Open Sound System subsystem of the Linux kernel version 2.6.39 and earlier. This flaw specifically affects non-x86 platforms and demonstrates how low-level kernel components can be exploited to compromise system stability through seemingly benign file access patterns. The vulnerability resides in the handling of audio sequencing operations through the /dev/sequencer device interface, which serves as a communication channel between user-space applications and the kernel's sound subsystem.
The technical implementation of this vulnerability stems from improper input validation within the OSS subsystem where integer underflow occurs during buffer size calculations for audio sequence operations. When a local user with write access to /dev/sequencer manipulates specific parameters, the kernel's handling of sequence data causes arithmetic operations to produce unexpected negative values that subsequently corrupt kernel memory structures. This integer underflow condition typically manifests when the system attempts to allocate or manipulate memory buffers based on malformed sequence data, leading to unpredictable memory corruption patterns that can ultimately result in system crashes or complete denial of service conditions.
The operational impact of CVE-2011-1476 extends beyond simple denial of service scenarios as the memory corruption can potentially be leveraged for more sophisticated attacks depending on the system configuration and available privileges. Local attackers who already possess write access to the sequencer device can exploit this vulnerability to destabilize system audio services or potentially escalate their privileges through careful manipulation of the corrupted kernel memory regions. The vulnerability's classification aligns with CWE-191, which specifically addresses integer underflow conditions, and demonstrates how such fundamental mathematical errors in kernel code can create persistent security risks across multiple platform architectures.
Mitigation strategies for this vulnerability require immediate kernel updates to version 2.6.39 or later where the integer underflow has been addressed through proper input validation and boundary checking mechanisms. System administrators should also implement strict access controls for the /dev/sequencer device to limit write permissions to authorized users only, though this represents a defensive measure rather than a complete solution. The vulnerability's presence in non-x86 platforms underscores the importance of comprehensive testing across all supported architectures during security patch deployment. Organizations should also consider implementing monitoring solutions to detect unusual patterns of sequencer device access that might indicate exploitation attempts, aligning with ATT&CK technique T1059 for command and script injection through legitimate system interfaces. The broader implications of this vulnerability highlight the critical need for robust input validation in kernel space operations and demonstrate how seemingly isolated subsystem flaws can create widespread system instability.