CVE-2012-6703 in Linux
Summary
by MITRE • 01/25/2023
Integer overflow in the snd_compr_allocate_buffer function in sound/core/compress_offload.c in the ALSA subsystem in the Linux kernel before 3.6-rc6-next-20120917 allows local users to cause a denial of service (insufficient memory allocation) or possibly have unspecified other impact via a crafted SNDRV_COMPRESS_SET_PARAMS ioctl call.
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Analysis
by VulDB Data Team • 01/25/2023
The vulnerability identified as CVE-2012-6703 represents a critical integer overflow flaw within the Advanced Linux Sound Architecture (ALSA) subsystem of the Linux kernel. This issue specifically affects the snd_compr_allocate_buffer function located in sound/core/compress_offload.c, which is responsible for managing compressed audio buffer allocations. The vulnerability manifests when processing crafted SNDRV_COMPRESS_SET_PARAMS ioctl calls, which are used to configure compressed audio streams in the kernel's sound subsystem. The integer overflow occurs during the calculation of buffer sizes, where malicious input values can cause the system to allocate insufficient memory, leading to potential system instability and denial of service conditions.
The technical implementation of this vulnerability stems from improper input validation and arithmetic handling within the kernel's compressed audio processing code. When a local user submits a specially crafted ioctl command with oversized parameter values, the integer overflow causes the buffer allocation calculation to wrap around or produce negative values. This results in the kernel attempting to allocate memory blocks that are either insufficient for the requested operation or completely invalid, creating a scenario where the system cannot properly manage audio buffer resources. The flaw is classified under CWE-190 as an integer overflow, specifically involving signed integer overflow in arithmetic operations. This type of vulnerability allows attackers to manipulate the memory allocation process and can potentially lead to memory corruption or system crashes.
The operational impact of CVE-2012-6703 extends beyond simple denial of service conditions, as it represents a potential vector for more sophisticated attacks within the kernel context. Local users with access to the system can exploit this vulnerability to cause system instability, potentially leading to complete system crashes or forced reboots that disrupt audio services and other system functions. The vulnerability is particularly concerning because it operates at kernel level, meaning successful exploitation can result in complete system compromise or enable further privilege escalation attacks. The attack requires local access and execution privileges, making it more difficult to exploit remotely but still presenting a significant risk in multi-user environments where malicious users might gain access to system resources. According to ATT&CK framework, this vulnerability aligns with T1068 (Exploitation for Privilege Escalation) and T1499 (Endpoint Denial of Service) tactics, as it can be used to gain elevated privileges or disrupt system services.
Mitigation strategies for CVE-2012-6703 focus primarily on kernel version updates and input validation improvements. The most effective solution involves upgrading to Linux kernel versions 3.6-rc6-next-20120917 or later, where the integer overflow has been addressed through proper bounds checking and input validation. System administrators should implement comprehensive patch management processes to ensure all kernel components are up to date with the latest security fixes. Additional protective measures include monitoring for suspicious ioctl activity, implementing proper access controls to limit local user privileges, and maintaining robust system logging to detect potential exploitation attempts. The vulnerability demonstrates the importance of rigorous input validation in kernel space operations and highlights the need for thorough security testing of system call interfaces. Organizations should also consider implementing kernel hardening techniques such as stack canaries and address space layout randomization to further reduce the attack surface and potential impact of similar vulnerabilities.