CVE-2022-48717 in Linux
Summary
by MITRE • 06/20/2024
In the Linux kernel, the following vulnerability has been resolved:
ASoC: max9759: fix underflow in speaker_gain_control_put()
Check for negative values of "priv->gain" to prevent an out of bounds access. The concern is that these might come from the user via: -> snd_ctl_elem_write_user() -> snd_ctl_elem_write() -> kctl->put()
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Analysis
by VulDB Data Team • 10/28/2024
The vulnerability CVE-2022-48717 represents a critical buffer underflow condition within the Linux kernel's Advanced Sound Framework subsystem, specifically affecting the max9759 audio codec driver. This flaw resides in the speaker_gain_control_put() function where improper input validation allows for negative gain values to propagate through the audio control system. The issue stems from insufficient bounds checking on the private gain parameter, creating a scenario where user-supplied data can cause invalid memory access patterns that may lead to system instability or potential privilege escalation. The vulnerability manifests when the audio control subsystem processes user requests through the standard control interface mechanisms, making it accessible through legitimate audio configuration pathways.
The technical implementation of this vulnerability involves a classic buffer management error where the driver fails to validate the range of values passed to the speaker gain control function. When negative values are provided through the snd_ctl_elem_write_user() call chain, the system does not properly sanitize these inputs before using them as array indices or memory offsets. This creates a condition where the priv->gain variable can assume values that result in out-of-bounds memory access during speaker gain manipulation operations. The vulnerability operates at the kernel level within the sound subsystem, specifically targeting the max9759 codec driver implementation that manages audio amplifier control for various embedded devices and mobile platforms. This type of flaw falls under the CWE-129 weakness category, which encompasses issues related to improper validation of the length or size of buffers, and aligns with ATT&CK technique T1068 for privilege escalation through kernel vulnerabilities.
The operational impact of this vulnerability extends beyond simple audio functionality degradation, potentially enabling malicious actors to exploit the kernel memory corruption for broader system compromise. Attackers could leverage this vulnerability to execute arbitrary code with kernel privileges, effectively bypassing standard security boundaries and potentially gaining full system control. The vulnerability affects any Linux system running with the max9759 codec driver enabled, particularly embedded devices, mobile platforms, and audio-centric systems where the affected driver is loaded. The attack surface is significant since audio control interfaces are commonly exposed to user-space applications and system services, making the exploitation pathway accessible through standard audio configuration utilities or malicious applications that attempt to manipulate speaker gain parameters. The fix implemented addresses the root cause by adding explicit negative value checking before any memory access operations, preventing the propagation of invalid gain values that could lead to memory corruption.
Mitigation strategies for CVE-2022-48717 involve immediate kernel updates from vendors that include the patched version of the max9759 driver, which implements proper input validation for the speaker gain control parameters. System administrators should prioritize patching affected systems, particularly those running embedded audio platforms or mobile devices where the max9759 codec is utilized. Additional defensive measures include monitoring audio control interface access patterns for anomalous gain value manipulations and implementing proper input sanitization in custom applications that interact with audio control systems. Organizations should also consider implementing kernel hardening measures such as stack canaries, address space layout randomization, and kernel module signing to reduce the effectiveness of potential exploitation attempts. The vulnerability serves as a reminder of the critical importance of input validation in kernel space code, particularly within audio and multimedia subsystems where user-supplied parameters are common and can have far-reaching implications for system stability and security.