CVE-2024-53238 in Linux
Riassunto
di VulDB • 01/07/2026
Based on the kernel log provided, here is an analysis of the crash and potential solutions.
### **Summary** The system experienced a **kernel panic/oops** in the `btusb` Bluetooth driver (specifically MediaTek-specific code) when disconnecting or releasing USB interfaces. The crash occurred during `usb_kill_anchored_urbs`, which suggests a race condition, use-after-free, or invalid memory access while trying to cancel pending USB transfers for an ISO endpoint.
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### **Detailed Analysis**
#### **1. Crash Location & Call Trace** - **Crash Point**: `usb_kill_anchored_urbs+0x60/0x168` - This function is responsible for killing all URBs (USB Request Blocks) in an anchor list to prevent them from completing after the device/driver has been removed. - **Trigger Path**: ``` btusb_mtk_release_iso_intf → btusb_mtk_disconnect → btusb_disconnect → usb_unbind_interface ... ``` - The crash happens during driver unbinding (`disconnect`), specifically when releasing an ISO (isochronous) interface for a MediaTek Bluetooth chip.
#### **2. Key Observations** - **Driver**: `btusb` with MediaTek-specific extensions (`btusb_mtk_*`). - **Context**: USB disconnect/unbind sequence initiated by user-space via `ioctl` (likely from `bluetoothctl`, `systemd-logind`, or a Bluetooth manager). - **Architecture**: ARM64 (`el0t_64_sync_handler`). - **Registers at Crash**: - `x2 = ffffff8087a91400` (likely an anchor list pointer) - `x1 = 0x0` (null or zeroed value, possibly indicating a missing structure member) - `x0 = ffffff80c0f25588` (pointer to URB or related data structure)
#### **3. Likely Causes** - **Race Condition**: The ISO interface is being released while URBs are still pending or in-flight, leading to access of freed memory. - **Driver Bug**: A bug in `btusb_mtk_release_iso_intf` where it assumes certain structures (like the anchor list) are valid when they may have already been cleaned up by a previous step. - **Hardware/USB Stack Issue**: The MediaTek Bluetooth chip or USB host controller is not handling disconnect gracefully, leaving dangling URBs.
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### **Solutions & Workarounds**
#### **1. Update Kernel and Drivers** This issue may have been fixed in newer kernel versions. Check if your distribution has updated the `btusb` driver: ```bash # For Debian/Ubuntu-based systems sudo apt update && sudo apt upgrade linux-image-$(uname -r) btusb-modules
# For Fedora/RHEL-based systems sudo dnf update kernel btusb ```
#### **2. Disable MediaTek-Specific Bluetooth Handling** If the crash persists, you can try disabling the MediaTek-specific code by blacklisting or unloading the `btusb` module temporarily to see if generic handling works (though this may break functionality): ```bash sudo rmmod btusb # Or blacklist it in /etc/modprobe.d/blacklist.conf: echo "blacklist btusb" | sudo tee -a /etc/modprobe.d/blacklist.conf ```
#### **3. Use a Different Bluetooth Adapter** If this is a hardware-specific issue with your MediaTek Bluetooth chip, consider using a USB Bluetooth adapter from a different vendor (e.g., Intel, Broadcom) which may have more stable driver support in Linux.
#### **4. Check for Known Bugs** Search the kernel bug tracker or your distribution’s bug database for: - `btusb_mtk_release_iso_intf crash` - `usb_kill_anchored_urbs btusb panic`
Example search terms: ```bash # On Ubuntu/Debian apt-cache policy linux-image-$(uname -r)
# Check dmesg for related warnings before the crash dmesg | grep -i "btusb\|usb.*error" ```
#### **5. Temporary Workaround: Avoid Hot-Unplug** If this occurs during hot-unplugging, avoid unplugging the Bluetooth device while it is in use or when the system is actively managing connections. Gracefully disconnect via software before physical removal.
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### **Debugging Steps for Developers/Advanced Users** 1. **Enable Kernel Debug Symbols**: Install `linux-image-dbg` (Debian/Ubuntu) to get meaningful stack traces with function names and line numbers. 2. **Check URB State**: Add debug prints in `btusb_mtk_release_iso_intf` to verify if the anchor list is valid before calling
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