Linux Kernel PCI BAR Resize Privilege Escalation

Executive Summary

This vulnerability in the Linux kernel involves a missing capability check in the __resource_resize_store() function. It allows writing to the resourceN_resize sysfs attribute to change a PCI device's Base Address Register (BAR) size without proper privileges. The fix adds a CAP_SYS_ADMIN check to prevent unauthorized users from performing BAR resize operations.

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Detection Guidance

This vulnerability can be detected by checking for unauthorized attempts to modify PCI BAR sizes via sysfs. Look for CAP_SYS_ADMIN checks failing in kernel logs or sysfs writes to resourceN_resize attributes. No specific commands are provided in the context.

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Impact Analysis

An unprivileged user could exploit this to modify PCI device configurations, potentially disrupting active drivers or causing system instability. This could lead to denial of service or unexpected behavior in systems relying on PCI devices.

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Mitigation Strategies

Apply the latest Linux kernel patches to ensure the CAP_SYS_ADMIN check is enforced in __resource_resize_store(). Monitor sysfs writes to resourceN_resize and restrict access to privileged users only.

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