CVE-2023-52821 - Linux Kernel Vulnerability Resolved: drm/panel Fixes Possible Null Pointer Dereference

In the ever-evolving world of technology, new vulnerabilities are being discovered and resolved continuously. This CVE-2023-52821 post focuses on a recent vulnerability found in the Linux kernel, which has now been fixed. The vulnerability concerns the drm/panel subsystem and deals with a possible null pointer dereference. This post will discuss the code snippet, link to original references, and provide details about the exploit.

The following code snippet highlights the change made to resolve the vulnerability

static int versatile_panel_get_modes(struct drm_panel *panel)
{
	struct drm_connector *connector = panel->connector;
	struct drm_display_mode *mode;

	mode = drm_mode_duplicate(connector->dev, &versatile_panel_mode);
	if (!mode) {
		dev_err(panel->dev, "failed to add mode %ux%u@%u\n",
			versatile_panel_mode.hdisplay,
			versatile_panel_mode.vdisplay,
			versatile_panel_mode.vrefresh);
		return ; // Added condition to check for null pointer dereference
	}

	drm_mode_set_name(mode);
	drm_mode_set_crtcinfo(mode, );
	connector->display_info.width_mm = mode->width_mm;
	connector->display_info.height_mm = mode->height_mm;
	return drm_add_modes_noedid(connector, 1, mode);
}

In this code snippet, the updated function versatile_panel_get_modes() checks if the return value of drm_mode_duplicate() is NULL, resulting in an assignment to mode. This check was added to avoid a null pointer dereference when drm_mode_duplicate() fails.

Links to Original References

This vulnerability was originally reported and fixed by Linux kernel developers. Here are the links to the original references for further information:

1. Linux Kernel Mailing List (LKML) Patch Submission: This link provides details about the patch that was submitted and later accepted to resolve the vulnerability in the Linux kernel.
2. CVE-2023-52821 NVD Entry: This link provides details about the vulnerability, including its impact, affected software, and references.
3. Linux Kernel Source Repository: This link provides the source code diff for the commit that contains the fix for the vulnerability in the Linux kernel.

Exploit Details

This vulnerability affected the drm/panel subsystem of the Linux kernel, which is responsible for managing display panels in various devices. A null pointer dereference could lead to undefined behavior, including system crash, data loss, or potentially even remote code execution.

By resolving this vulnerability, the Linux kernel developers have prevented possible exploits arising from the absence of a proper pointer check. This fix ensures that the versatile_panel_get_modes() function returns an appropriate error code when drm_mode_duplicate() fails, thus avoiding null pointer dereferences.

Conclusion

The Linux kernel developers have successfully fixed the vulnerability regarding possible null pointer dereferences in the drm/panel subsystem. With code changes and thorough testing, the patched kernel ensures system stability and security. As always, it is essential to stay up-to-date with the most recent patches and updates to ensure your systems are protected from known vulnerabilities like CVE-2023-52821.

Timeline

Published on: 05/21/2024 16:15:20 UTC
Last modified on: 05/24/2024 01:14:35 UTC