CVE-2022-48878
📋 TL;DR
A use-after-free vulnerability in the Linux kernel's Bluetooth subsystem allows local attackers to cause system crashes or potentially execute arbitrary code during system shutdown. This affects Linux systems with Qualcomm Atheros Bluetooth hardware when the HCI device fails to open properly. The vulnerability occurs during system reboot when the driver attempts to flush buffers that have already been freed.
💻 Affected Systems
- Linux kernel
📦 What is this software?
Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →⚠️ Risk & Real-World Impact
Worst Case
Local privilege escalation leading to kernel compromise and full system control, though this requires specific timing and conditions during shutdown.
Likely Case
System crash or kernel panic during reboot/shutdown, causing denial of service and potential data loss.
If Mitigated
Minor system instability during shutdown with no persistent effects if proper access controls prevent local attackers.
🎯 Exploit Status
Exploitation requires local access and specific timing during system shutdown. The vulnerability is triggered by the shutdown process itself rather than a traditional exploit payload.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in kernel commits: 272970be3dabd24cbe50e393ffee8f04aec3b9a8, 908d1742b6e694e84ead5c62e4b7c1bfbb8b46a3, e84ec6e25df9bb0968599e92eacedaf3a0a5b587, ea3ebda47dd56f6e1c62f2e0e1b6e1b0a973e447
Vendor Advisory: https://git.kernel.org/stable/c/272970be3dabd24cbe50e393ffee8f04aec3b9a8
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing the fix commits. 2. For distributions: Use package manager to update kernel package. 3. Rebuild kernel if using custom kernel. 4. Reboot system to load patched kernel.
🔧 Temporary Workarounds
Disable Qualcomm Bluetooth module
linuxPrevent loading of the vulnerable hci_uart driver module
echo 'blacklist hci_uart' >> /etc/modprobe.d/blacklist.conf
rmmod hci_uart
Disable Bluetooth service
linuxStop Bluetooth service to prevent HCI device initialization
systemctl stop bluetooth
systemctl disable bluetooth
🧯 If You Can't Patch
- Restrict local user access to prevent triggering during shutdown
- Implement monitoring for system crashes during reboot and investigate any occurrences
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if hci_uart module is loaded: lsmod | grep hci_uart && uname -rCheck Version:
uname -rVerify Fix Applied:
Verify kernel version is after fix commits and test system reboot with Bluetooth hardware present📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages during shutdown
- Use-after-free errors in kernel logs
- Systemd shutdown process failures
Network Indicators:
- None - local vulnerability only
SIEM Query:
source="kernel" AND ("use-after-free" OR "KASAN" OR "tty_driver_flush_buffer") AND process="systemd-shutdow"