Vulnerability in Kernel package: proc/vmcore
Summary
GSD-2021-1002469: proc/vmcore: fix clearing user buffer by properly using clear_user(). Affects Kernel versions >= 997c136f518c5debd63847e78e2a8694f56dcf90, < a8a917058faf4abaec9fb614bb6d5f8fe3529ec6. No fix is published. How to fix ↓
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Background
The Kernel package is a crucial component of the Linux operating system, responsible for managing core system functions and providing an interface between hardware and software. It includes various subsystems, such as process management, memory management, and device drivers. The proc/vmcore module specifically handles the generation of a crash dump file (vmcore) when the system encounters a kernel panic or crash. This file contains valuable information for debugging and analyzing the cause of the crash.
Vulnerability Detail
The vulnerability in proc/vmcore arises from improper usage of the clear_user() function, which is responsible for clearing user buffers. Due to this flaw, an attacker may be able to access sensitive information present in the user buffer. The impact and attack plausibility of this vulnerability have not been proven yet. However, if successfully exploited, it could lead to unauthorized disclosure of kernel memory contents, potentially exposing sensitive data or facilitating further attacks.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a temporary workaround, users can apply the patch provided in commit a8a917058faf4abaec9fb614bb6d5f8fe3529ec6 manually. Here is an example of the patch:
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -123,7 +123,7 @@ static ssize_t vmcore_write(struct file *file, const char __user *buf,
goto out;
}
-#ifdef CONFIG_PROC_VMCORE_CLEAR
+#ifdef CONFIG_PROC_VMCORE_CLEAR_FIX
clear_user(vmcore_buf, vmcore_limit);
ret = copy_from_user(vmcore_buf, buf, count);
if (ret) {
Conclusion
In conclusion, the vulnerability in the Kernel package's proc/vmcore module can potentially allow unauthorized access to sensitive information. It is crucial to update the Linux Kernel to version v5.10.83 or later to mitigate this vulnerability. Applying the provided patch or using Vulert Playground can serve as temporary measures until the Kernel update is applied. For further support and assistance in vulnerability remediation, please contact DevNack.com.
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FAQ
If successfully exploited, this vulnerability could allow an attacker to access sensitive information present in the user buffer, potentially leading to unauthorized disclosure of kernel memory contents.
You can use Vulert Playground (https://vulert.com/scanner) to check if your system is affected by this vulnerability. Vulert monitors and alerts in real-time for open-source vulnerabilities without requiring access to the code or installation. Simply upload your manifest file (e.g., package-lock.json) to the Vulert Playground and it will provide information on any vulnerabilities present in your software.
Yes, the vulnerability has been fixed in Linux Kernel version v5.10.83. It is recommended to update your Kernel to this version or later to ensure the proper usage of the clear_user() function.
Yes, a temporary workaround is to manually apply the patch provided in commit a8a917058faf4abaec9fb614bb6d5f8fe3529ec6. However, it is strongly advised to update the Kernel to the fixed version as soon as possible.
You can find more information about this vulnerability in the official Linux Kernel repository. The vulnerability details can be accessed at the following link: https://github.com/cloudsecurityalliance/gsd-database/blob/main/2021/1002xxx/GSD-2021-1002469.json
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