CVE-2021-47097 in Linux
الملخص
بحسب VulDB • 11/05/2026
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 an **Elantech** touchpad (indicated by `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 either: - Unmapped (`mapping:0000000000000000`) - Part of a freed page (`refcount:0`) - Or a null/invalid pointer.
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### **2. Likely Cause** This is a **known issue** with certain **Elantech touchpads** on Linux kernels, particularly when: 1. The `psmouse` driver fails to correctly initialize the touchpad. 2. There is a mismatch between the driver and the touchpad firmware. 3. The kernel version has a bug in the `elantech` protocol handling.
Common triggers: - Booting with certain kernel parameters. - Using a kernel version between **5.10–5.15** (where this bug was prevalent). - Hardware-specific quirks not yet handled by the driver.
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### **3. Recommended Solutions**
#### **A. Update Your Kernel** This issue has been fixed in newer kernel versions. - **If you’re on Ubuntu/Debian:** ```bash sudo apt update sudo apt install --install-recommends linux-generic-hwe-22.04 # For Ubuntu 22.04 ``` - **If you’re on Arch Linux:** ```bash sudo pacman -Syu linux ``` - **If you’re on Fedora:** ```bash sudo dnf update kernel ```
#### **B. Blacklist or Replace the `psmouse` Driver** If updating the kernel is not an option, you can try forcing the touchpad to use a different driver.
1. **Try the `synaptics` driver instead:** Add this to your kernel boot parameters (edit `/etc/default/grub`): ``` psmouse.proto=exps ``` Then update GRUB: ```bash sudo update-grub # Debian/Ubuntu sudo grub2-mkconfig -o /boot/grub2/grub.cfg # Fedora/RHEL ```
2. **Blacklist `psmouse` and use `libinput`:** Some systems work better with `libinput` directly. Create a udev rule: ```bash sudo nano /etc/udev/rules.d/99-elantech-touchpad.rules ``` Add: ``` ACTION=="add", SUBSYSTEM=="serio", ATTRS{id}=="001f:04f3:0001", ATTR{protocol}="exps"
``` *(Note: Adjust `id` based on your device. Use `lsinput` or `dmesg` to find it.)*
#### **C. Disable Touchpad Temporarily (Workaround)** If the system is unstable, you can disable the touchpad at boot: - Add to GRUB boot parameters: ``` psmouse.synaptics_intertouch=0 ``` Or: ``` psmouse.proto=bare ```
#### **D. Check for BIOS/UEFI Updates** Some Elantech touchpad issues are resolved by updating your laptop’s BIOS/UEFI firmware, as it may include better HID/PS/2 compatibility.
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### **4. How to Gather More Information** If the issue persists, run: ```bash dmesg | grep -i psmouse dmesg | grep -i elantech ``` Also, check your kernel version: ```bash uname -r ```
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### **Conclusion** This is a **driver-level bug** in the `psmouse` module when handling Elantech touchpads. **Best fix
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