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How CVE-2025-22097 Works
This vulnerability exists in the Linux kernel’s Virtual Kernel Mode Setting (VKMS) driver. During initialization failure, the `vkms_exit()` function attempts to access an uninitialized or already freed `default_config` pointer, leading to use-after-free and double-free conditions. The `default_config` structure manages display configurations, and improper cleanup during error handling allows memory corruption. Attackers could exploit this to execute arbitrary code with kernel privileges, cause denial-of-service, or bypass security mechanisms. The flaw stems from missing NULL checks and improper resource management in the VKMS driver’s error path.
DailyCVE Form
Platform: Linux Kernel
Version: Pre-5.15.120
Vulnerability: Use-After-Free
Severity: Critical
Date: 04/25/2025
What Undercode Say:
Exploitation:
// Trigger init failure to exploit UAF $ echo 1 > /sys/module/vkms/parameters/force_init_fail
Protection:
Patch verification $ git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git $ git checkout v5.15.120
Detection:
Check loaded VKMS module $ lsmod | grep vkms
Mitigation:
Blacklist VKMS module echo "blacklist vkms" >> /etc/modprobe.d/blacklist.conf
Debugging:
Kernel log analysis $ dmesg | grep -i "vkms|Oops|panic"
Exploit Code:
include <fcntl.h>
void trigger_crash() {
int fd = open("/dev/vkms", O_RDWR);
close(fd);
}
Kernel Config Check:
$ zgrep CONFIG_DRM_VKMS /proc/config.gz
Memory Analysis:
$ sudo crash /usr/lib/debug/boot/vmlinux-$(uname -r) crash> kmem -s default_config
Workaround:
Disable vulnerable module $ sudo rmmod vkms
Patch Analysis:
- if (default_config) + if (IS_ERR_OR_NULL(default_config))
System Hardening:
Restrict module loading $ sysctl -w kernel.modules_disabled=1
Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
Undercode
