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In the Linux kernel, a memory leak vulnerability was discovered in the AMD platform driver, specifically within the `wbrf_record()` function . This function allocates a temporary memory buffer using `kcalloc()` to handle data related to Wireless Band RF (WBRF) operations . After the allocation, the function calls `acpi_evaluate_dsm()` to communicate with the system firmware. The vulnerability arises because if `acpi_evaluate_dsm()` fails, the error handling path in the original code did not free the previously allocated `tmp` buffer . This missing `kfree()` operation means that every time this specific error condition occurs, a small amount of kernel memory becomes unreachable and is wasted . Over time, or if an attacker can repeatedly trigger this error path, the accumulated leaked memory could lead to system instability or a denial of service due to memory exhaustion . The issue was introduced in kernel version 6.8 and has been fixed in subsequent stable releases by adding the necessary `kfree(tmp)` call in the error path .
dailycve form:
Platform: Linux
Version: 6.8 to 6.18.7
Vulnerability: Memory Leak
Severity: Unknown
Date: 2026-02-04
Prediction: Patches available
What Undercode Say:
Analytics:
The vulnerability is present in the AMD x86 platform driver affecting the WBRF (Wireless Band RF) functionality . It impacts Linux kernel versions starting from 6.8 up to, but not including, the patched versions . The issue was resolved in specific stable kernel updates, including 6.12.68, 6.18.8, and 6.19-rc7 . Distribution trackers show that long-term support releases like Debian Bullseye and Bookworm are not affected, while newer releases like Ubuntu 25.10 and Debian Trixie contain the vulnerable code . The core problem is a missing deallocation function in an error path, classified as a resource cleanup flaw.
Bash Commands & Code:
Check your current kernel version uname -r Check if the AMD WBRF driver module is loaded lsmod | grep wbrf Monitor kernel memory usage for potential leaks (look for growing SUnreclaim value) watch -n 5 'grep -E "MemTotal|MemFree|Slab|SUnreclaim" /proc/meminfo' If kmemleak is enabled in your kernel, use it to scan for unreferenced objects First, trigger a scan echo scan > /sys/kernel/debug/kmemleak Then, view the results cat /sys/kernel/debug/kmemleak | grep -i wbrf
The vulnerable code pattern involved allocating memory and not freeing it on error:
// Vulnerable pseudo-code:
tmp = kcalloc(...);
// ... other code ...
if (acpi_evaluate_dsm(...)) {
// Error path: Missing kfree(tmp) causes leak
return -EIO;
}
The fix adds the missing cleanup:
// Patched pseudo-code:
tmp = kcalloc(...);
// ... other code ...
if (acpi_evaluate_dsm(...)) {
kfree(tmp); // Properly free memory on error
return -EIO;
}
How Exploit:
This is a memory leak vulnerability, not a direct code execution or privilege escalation flaw. An exploit would involve repeatedly triggering the error condition in the `wbrf_record()` function where `acpi_evaluate_dsm()` fails . If an attacker with local access can induce these failures, they could cause the kernel to leak memory each time. Over a prolonged period, this could lead to memory pressure, potentially causing system services to crash or the entire system to become unresponsive (denial of service) .
Protection from this CVE:
The primary and recommended protection is to update the Linux kernel to a patched version . This includes versions 6.12.68 or later, 6.18.8 or later, and 6.19-rc7 or later . System administrators should apply the latest stable kernel updates from their Linux distribution. As a temporary workaround, if the system does not require WBRF functionality, one might explore options to blacklist the relevant kernel module, though this could impact hardware features . Continuous monitoring of kernel memory statistics can help detect if the leak is occurring on systems that cannot be immediately patched .
Impact:
Successful exploitation leads to the gradual exhaustion of system memory . This can degrade system performance, cause applications to fail due to out-of-memory errors, and ultimately result in a denial of service where the system becomes unstable or crashes. The impact is considered a reliability and availability issue rather than a breach of data confidentiality or integrity .
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Sources:
Reported By: nvd.nist.gov
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