Executive Summary

This vulnerability exists in the Linux kernel's hardware monitoring (hwmon) subsystem, specifically in the powerz driver. It involves improper handling of USB request blocks (URBs) when a signal interrupt occurs during a wait operation.

The function wait_for_completion_interruptible_timeout() returns -ERESTARTSYS when interrupted by a signal, but the original code only checked for a timeout (return value 0) and did not properly handle the signal case. As a result, usb_kill_urb() was not called on signal interrupts, causing the system to read from an unfilled transfer buffer where no valid data was received.

The fix involves capturing the return value properly and ensuring usb_kill_urb() is called both on timeout and signal interrupt cases to abort the URB and prevent invalid reads.

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Impact Analysis

This vulnerability can lead to the system reading invalid or uninitialized data from the USB transfer buffer when a signal interrupt occurs. This could cause incorrect behavior or data corruption in applications relying on the hardware monitoring data.

While no direct security impact such as privilege escalation or code execution is described, the improper handling of URBs could potentially lead to system instability or unexpected errors in hardware monitoring functions.

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Mitigation Strategies

The vulnerability has been resolved in the Linux kernel by fixing the handling of usb_kill_urb() on signal interrupts in the hwmon (powerz) driver.

To mitigate this vulnerability immediately, you should update your Linux kernel to a version that includes this fix.

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