Vulnerability in drm/edid Package: Connector_bad_edid() Function Allows num_of_ext to Exceed num_blocks
Summary
GSD-2021-1001900: drm/edid: In connector_bad_edid() cap num_of_ext by num_blocks read. Affects Kernel versions >= e11f5bd8228fc3760c221f940b9f6365dbf3e7ed, < 09f3946bb452918dbfb1982add56f9ffaae393dc. No fix is published. How to fix ↓
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Background
The drm/edid package is a component of the Linux Kernel that handles Extended Display Identification Data (EDID) for display connectors. EDID is a standardized data structure provided by displays to describe their capabilities and characteristics. The connector_bad_edid() function within the package is responsible for validating the EDID data received from a display connector. However, a vulnerability exists in this function that allows the 'num_of_ext' value to exceed the 'num_blocks' value, potentially leading to memory corruption or other security issues.
Vulnerability Detail
The vulnerability in the drm/edid package arises from a lack of proper bounds checking in the connector_bad_edid() function. By not properly capping the 'num_of_ext' value by the 'num_blocks' value, an attacker could craft a malicious EDID data structure that exceeds the expected size, causing memory corruption or other undefined behavior. This could potentially be exploited to execute arbitrary code, escalate privileges, or crash the system. The vulnerability was introduced in Linux Kernel version v5.7 and has been fixed in version v5.14.14.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a workaround, users can disable the affected display connector or disconnect the display device to prevent potential exploitation of the vulnerability. However, this may result in the loss of display functionality for the affected connector.
Conclusion
The vulnerability in the drm/edid package's connector_bad_edid() function allows the 'num_of_ext' value to exceed the 'num_blocks' value, potentially leading to memory corruption or other security issues. It is crucial to update the Linux Kernel to version v5.14.14 or later to fix this vulnerability. Alternatively, users can disable the affected display connector or disconnect the display device as a temporary workaround. For further support on vulnerability remediation, please contact DevNack.com.
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FAQ
The vulnerability could potentially allow an attacker to execute arbitrary code, escalate privileges, or crash the system.
You can use the Vulert Playground (https://vulert.com/scanner) to check if your system is affected by this vulnerability. Simply upload your package-lock.json file and Vulert will analyze it for any open-source vulnerabilities, including this one.
At the time of this report, there is no known public exploit for this vulnerability. However, it is still important to apply the fix to ensure the security of your system.
While updating the kernel is the recommended solution, you can mitigate the vulnerability by disabling the affected display connector or disconnecting the display device. However, this may result in the loss of display functionality for the affected connector.
This vulnerability specifically affects the drm/edid package in the Linux Kernel. However, it is always recommended to keep all software and packages up to date to ensure the overall security of your system.
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