Executive Summary

This vulnerability exists in the Linux kernel's I2C driver, specifically in the handling of the I2C_TIMEOUT ioctl command.

The ioctl accepts a user-provided timeout value in multiples of 10 milliseconds. Although the input is checked against the maximum integer value (INT_MAX), it is then multiplied by 10 without proper bounds checking, which can cause an integer overflow.

A malicious user can supply a large timeout value that passes the initial check but overflows when multiplied by 10. This overflow results in a truncated 32-bit unsigned value that bypasses further internal checks.

This truncated value is assigned to a signed 32-bit integer representing the timeout, which can be interpreted as a negative number. When this negative timeout is used in kernel functions, it triggers warnings and causes premature returns, leaving the SMBus controller's state machine corrupted and unrecoverable.

Overall, this leads to a local Denial of Service (DoS) condition by disrupting the SMBus controller's normal operation.

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Impact Analysis

This vulnerability can cause a local Denial of Service (DoS) on affected Linux systems.

By exploiting the integer overflow in the I2C_TIMEOUT ioctl, an attacker with local access can corrupt the SMBus controller's state machine, causing it to become unrecoverable.

This disruption can lead to malfunctioning of hardware components that rely on the SMBus, potentially affecting system stability or functionality.

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Compliance Impact

The provided information does not specify any direct impact of this vulnerability on compliance with common standards and regulations such as GDPR or HIPAA.

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Detection Guidance

This vulnerability manifests as a persistent "schedule_timeout: wrong timeout value" warning in the Linux kernel logs, accompanied by SMBus controller state machine corruption.

To detect this issue on your system, you can monitor the kernel logs for the specific warning message.

• Use the command: dmesg | grep 'schedule_timeout: wrong timeout value'
• Check system logs with: journalctl -k | grep 'schedule_timeout: wrong timeout value'

These commands help identify if the kernel has logged the warning related to this vulnerability, indicating potential exploitation or occurrence.

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Mitigation Strategies

The vulnerability is caused by an integer overflow in the I2C_TIMEOUT ioctl handling in the Linux kernel.

Immediate mitigation involves updating the Linux kernel to a version where this issue has been fixed, specifically where the user argument to the ioctl is properly bounded to INT_MAX / 10.

Until the kernel is updated, restrict untrusted users from accessing the I2C_TIMEOUT ioctl interface to prevent exploitation.

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