In the world of cybersecurity, vulnerabilities are constantly being discovered and patched, aiming to keep our systems safe from potential exploits or attacks. One such vulnerability has been resolved, which was present in the Linux kernel, an important component of the operating system. The issue revolves around the tracing/trigger module, where it failed to return an error if there was an issue with allocating a snapshot. This situation could potentially be exploited by malicious actors.

In this post, we will dive into the details of this specific vulnerability, its impact, the code snippet to fix the issue, and links to the original references. Buckle up, and let's patch this kernel together!

Details of the Vulnerability

The affected module in the Linux kernel is the tracing/trigger function, where an error is supposed to be returned if the system fails to allocate a snapshot. However, due to the vulnerability, the function ends up returning instead of the error code, which would indicate a success in registering the snapshot trigger when it actually failed. This situation might lead to potential security vulnerabilities if left unresolved.

The fix for this issue is relatively simple and involves updating the register_snapshot_trigger() function to return the correct error code in case of failure. This will ensure that the appropriate error handling is performed by the system when dealing with similar scenarios. The code snippet provided below demonstrates the fix being applied to the function:

Code Snippet

diff --git a/kernel/trace/trace_trigger.c b/kernel/trace/trace_trigger.c
index 7d46f84e1708..4eac35b2ca82 100644
--- a/kernel/trace/trace_trigger.c
+++ b/kernel/trace/trace_trigger.c
@@ -156,8 +156,10 @@ static int register_snapshot_trigger(struct trace_event_file *file)
 
 	/* If we don't have a snapshot buffer, create it */
 	if (!tr->allocated_snapshot) {
-		if (trace_alloc_snapshot(tr))
-			return ;
+		ret = trace_alloc_snapshot(tr);
+		if (ret)
+			return ret;
+
 		/* Still need "snapshot" event trigger to account for curr_ret */
 		ret = event_create_dir(tr, file);
 		if (ret)

Original References and Exploit Details

For more information on this vulnerability, how the fix has been applied, and the impact it might have had, refer to the following resources:

1. Linux Kernel Git Repository: The official repository for the Linux kernel, where the vulnerability was identified and the fix introduced. Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7a1138565eaec6961e19792feda7d836f75c5f36

2. Linux Kernel Mailing List Archive: The archived mailing list where the vulnerability was discussed, along with the proposed patch. Link: https://lkml.org/lkml/2022/1/19/957

3. National Vulnerability Database (NVD): This resource will provide additional details about the vulnerability, its impact on various systems, and the Common Vulnerability Scoring System (CVSS) to understand the severity of this vulnerability. Link: https://nvd.nist.gov/vuln/detail/CVE-2024-26920 (Note: This link will be live once the vulnerability is officially published in the NVD database)

In conclusion, it is crucial to be aware of such vulnerabilities and ensure that patches are applied to prevent potential exploits or attacks. As Linux kernel is a fundamental part of several operating systems and crucial to their functioning, addressing such vulnerabilities swiftly and efficiently becomes indispensable. Stay safe out there, and make sure to keep your systems up-to-date and secure.

Timeline

Published on: 04/17/2024 16:15:08 UTC
Last modified on: 05/29/2024 05:25:02 UTC