CVE-2022-24958 Overview
A memory management vulnerability exists in the Linux kernel's USB gadget legacy driver (drivers/usb/gadget/legacy/inode.c) through version 5.16.8. The vulnerability arises from improper handling of dev->buf release operations, which can lead to memory corruption conditions. This flaw affects the USB gadget filesystem interface used for implementing USB device functionality on Linux systems.
Critical Impact
Local attackers with low privileges can exploit this memory mismanagement vulnerability to potentially achieve high impact on system confidentiality, integrity, and availability through memory corruption.
Affected Products
- Linux Kernel (through version 5.16.8)
- Fedora 34 and 35
- Debian Linux 9.0
- NetApp H300S, H500S, H700S Firmware
- NetApp H300E, H500E, H700E Firmware
- NetApp H410S and H410C Firmware
Discovery Timeline
- February 11, 2022 - CVE-2022-24958 published to NVD
- November 21, 2024 - Last updated in NVD database
Technical Details for CVE-2022-24958
Vulnerability Analysis
The vulnerability is classified under CWE-763 (Release of Invalid Pointer or Reference), indicating improper memory management in the USB gadget legacy driver. The flaw occurs in the drivers/usb/gadget/legacy/inode.c file where the kernel mishandles the release of the dev->buf buffer.
The vulnerability allows a local attacker with low-level privileges to exploit the memory handling flaw without requiring user interaction. Successful exploitation can result in high impact to confidentiality, integrity, and availability of the affected system. The issue specifically manifests during error handling paths where the buffer release and state management are not properly synchronized.
Root Cause
The root cause lies in improper synchronization and state management when releasing the dev->buf buffer in the USB gadget filesystem driver. Two specific issues were identified:
When usb_gadget_probe_driver() fails, the code would free dev->buf and set it to NULL without proper lock synchronization, leading to potential race conditions.
When handling an existing dev->buf, the code would free the newly allocated buffer (kbuf) but continue to the fail path while holding a spinlock, causing improper state transitions.
Attack Vector
The attack vector is local, requiring the attacker to have low-privilege access to the system. The attacker can trigger the vulnerability through interactions with the USB gadget filesystem interface. Due to the memory mismanagement, an attacker could potentially cause use-after-free conditions or other memory corruption scenarios that may lead to privilege escalation or denial of service.
// Patch 1: Proper lock handling when dev->buf already exists
// Source: https://github.com/torvalds/linux/commit/89f3594d0de58e8a57d92d497dea9fee3d4b9cda
spin_lock_irq (&dev->lock);
value = -EINVAL;
if (dev->buf) {
+ spin_unlock_irq(&dev->lock);
kfree(kbuf);
- goto fail;
+ return value;
}
dev->buf = kbuf;
// Patch 2: Clear related members properly when goto fail
// Source: https://github.com/torvalds/linux/commit/501e38a5531efbd77d5c73c0ba838a889bfc1d74
value = usb_gadget_probe_driver(&gadgetfs_driver);
if (value != 0) {
- kfree (dev->buf);
- dev->buf = NULL;
+ spin_lock_irq(&dev->lock);
+ goto fail;
} else {
/* at this point "good" hardware has for the first time
* let the USB the host see us. alternatively, if users
Detection Methods for CVE-2022-24958
Indicators of Compromise
- Unexpected kernel crashes or panics related to USB gadget subsystem
- Memory corruption errors in kernel logs referencing gadgetfs or inode.c
- Suspicious local privilege escalation attempts following USB gadget interactions
Detection Strategies
- Monitor kernel logs for memory corruption or use-after-free errors in the USB gadget subsystem
- Implement kernel address sanitizer (KASAN) to detect memory safety violations
- Use kernel debugging tools to track dev->buf allocation and release patterns
Monitoring Recommendations
- Enable kernel audit logging for USB gadget filesystem operations
- Deploy SentinelOne Singularity platform for real-time kernel-level threat detection
- Monitor for unusual privilege escalation attempts on systems with USB gadget functionality enabled
How to Mitigate CVE-2022-24958
Immediate Actions Required
- Update the Linux kernel to a patched version (5.16.9 or later)
- Apply vendor-specific patches from Fedora, Debian, or NetApp as applicable
- Restrict access to USB gadget filesystem interfaces to trusted users only
- Consider disabling USB gadget functionality if not required
Patch Information
The vulnerability has been addressed through two kernel commits that fix the memory management issues:
- Linux Kernel Commit 89f3594d0de58e8a57d92d497dea9fee3d4b9cda - Fixes the issue of releasing an existing dev->buf with proper lock handling
- Linux Kernel Commit 501e38a5531efbd77d5c73c0ba838a889bfc1d74 - Clears related members properly when going to fail path
Additional vendor advisories:
Workarounds
- Disable the USB gadget legacy driver (gadgetfs) if not required for system functionality
- Restrict access to /dev/gadget device files using filesystem permissions
- Use Linux Security Modules (SELinux/AppArmor) to limit processes that can interact with USB gadget interfaces
# Configuration example: Disable gadgetfs module loading
echo "blacklist gadgetfs" >> /etc/modprobe.d/blacklist.conf
echo "install gadgetfs /bin/false" >> /etc/modprobe.d/blacklist.conf
update-initramfs -u
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
