CVE-2021-47097 in Linux
Сводка
по VulDB • 22.05.2026
Based on the kernel log snippet provided, here is an analysis of the issue, its likely cause, and recommended solutions.
### **1. Summary of the Issue** - **Component:** `psmouse` (PS/2 Mouse driver) - **Device:** Likely a **Synaptics** or **Elantech** touchpad (indicated by `synaptics_send_cmd` and `elantech_query_info` in the stack trace). - **Error Type:** **Kernel Oops/Panic** due to a **NULL pointer dereference** or **invalid memory access**. - **Key Indicator:** ``` The buggy address belongs to the page: page:00000000bc35e189 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1024d7 ``` This indicates the kernel tried to access memory at an address that is **not properly mapped** or is **freed/corrupted**. The `refcount:0` and `mapping:0000000000000000` suggest the page is either uninitialized, freed, or invalid.
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### **2. Likely Causes** 1. **Hardware/Touchpad Firmware Bug:** The touchpad controller may be sending malformed data or responding incorrectly during initialization (`psmouse_probe` → `psmouse_switch_protocol` → `psmouse_extensions`). 2. **Driver Bug in `psmouse` Module:** A race condition or null pointer dereference in the Synaptics/Elantech-specific code within the `psmouse` driver. 3. **Kernel Version Bug:** This may be a known bug in your specific kernel version. Check if your kernel is up-to-date. 4. **ACPI/BIOS Issue:** Incorrect ACPI tables or BIOS settings related to the touchpad can cause the driver to misinterpret hardware state.
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### **3. Recommended Solutions**
#### **A. Immediate Workaround: Disable Touchpad Initialization** If the system is booting but crashing during touchpad initialization, you can try disabling the touchpad driver temporarily: 1. Edit GRUB configuration: ```bash sudo nano /etc/default/grub ``` 2. Add one of the following to `GRUB_CMDLINE_LINUX_DEFAULT`: - **Disable psmouse entirely:** ``` psmouse.proto=none ``` - **Disable Synaptics-specific features:** ``` psmouse.synaptics_intertouch=0 ``` - **Disable Elantech-specific features:** ``` psmouse.elantech=0 ``` 3. Update GRUB and reboot: ```bash sudo update-grub sudo reboot ```
#### **B. Update Kernel and Firmware** 1. **Update your kernel** to the latest stable version. This bug may have been fixed in newer kernels. 2. **Update BIOS/UEFI firmware** from your laptop manufacturer’s website. Touchpad firmware bugs are often resolved in BIOS updates.
#### **C. Check for Known Bugs** Search for your kernel version and touchpad model (e.g., "Elantech touchpad kernel oops psmouse") on: - [Kernel Bugzilla](https://bugzilla.kernel.org/)
- Your Linux distribution’s bug tracker (e.g., Ubuntu Launchpad, Fedora Bugzilla).
#### **D. Alternative: Use `libinput` Instead of `psmouse`** If you’re using X11, ensure you’re using `libinput` instead of the older `synaptics` driver: ```bash sudo apt install xserver-xorg-input-libinput # Debian/Ubuntu sudo dnf install xorg-x11-drv-libinput # Fedora ``` Then, create a config file `/etc/X11/xorg.conf.d/40-libinput.conf` to force `libinput`: ```conf Section "InputClass" Identifier "libinput touchpad catchall" MatchIsTouchpad "on" Driver "libinput" EndSection ```
#### **E. Debugging Further** If the issue persists, collect more debug info: 1. Enable kernel debug symbols (if available). 2. Check `dmesg` for earlier warnings before the crash. 3. Try booting with `acpi=off` or `acpi=noirq` to rule out ACPI issues (note: this may disable other hardware features).
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### **4. Conclusion** This is a **kernel-level crash** in
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