CVE-2022-50378 in Linux
Zusammenfassung
von VulDB • 20.05.2026
Based on the KASAN (Kernel Address Sanitizer) log provided, here is an analysis of the issue:
### **Summary** This is a **Use-After-Free (UAF)** or **Double-Free** bug in the Linux kernel, specifically within the **Meson DRM driver** (`meson_drm`) and its HDMI sub-component (`meson_dw_hdmi`).
The memory was **freed** during the driver removal/unbind process (`meson_dw_hdmi_remove` → `component_unbind_all`), but it was **allocated** by **Task 0** (likely the idle task or a kernel thread) and was still being accessed or referenced after being freed.
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### **Detailed Breakdown**
#### **1. The Freed Stack (Who freed the memory?)** The memory was freed by **Task 2695** during a module unload or device removal sequence: ``` kfree+0x110/0x35c → release_nodes+0xf0/0x16c → devres_release_group+0x180/0x270 → component_unbind+0x128/0x1e0 → component_unbind_all+0x1b8/0x264 → meson_drv_unbind+0x1a0/0x2ac [meson_drm]
→ take_down_aggregate_device+0xb0/0x160 → component_del+0x18c/0x360 → meson_dw_hdmi_remove+0x28/0x40 [meson_dw_hdmi]
→ platform_remove+0x64/0xb0 → device_remove+0xb8/0x154 → driver_detach+0xac/0x1b0 → bus_remove_driver+0x158/0x29c → driver_unregister+0x70/0xb0 → platform_driver_unregister+0x20/0x2c → meson_dw_hdmi_platform_driver_exit+0x1c/0x30 [meson_dw_hdmi]
→ __do_sys_delete_module+0x288/0x400 ``` - **Context**: The `meson_dw_hdmi` platform driver is being unregistered (likely via `rmmod` or system shutdown). - **Action**: During cleanup, `component_unbind_all` is called, which triggers `devres_release_group`, leading to `kfree`.
#### **2. The Allocated Stack (Who allocated the memory?)** The memory was allocated by **Task 0**: ``` [ +0.000007] Allocated by task 0:
[ +0.000007] (stack is not available)
``` - **Task 0** is typically the **idle task** or a **kernel worker thread**. - The stack is not available, which often happens if the allocation occurred in a context where stack traces are not captured (e.g., early boot, interrupt context, or a very low-level kernel path).
#### **3. The Bug** - **Buggy Address**: `ffff000020c39000` - **Issue**: The memory at this address was freed during driver removal, but it was still in use or referenced by **Task 0**. This suggests: - **Use-After-Free**: Task 0 is accessing the memory after it has been freed. - **Double-Free**: Task 0 might be trying to free the same memory again (less likely given the "allocated by task 0" message, but possible if the allocator detects a double free). - **Race Condition**: A race between the driver removal (Task 2695) and some ongoing operation in Task 0 (e.g., a delayed work item, interrupt handler, or hardware completion callback).
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### **Likely Causes** 1. **Missing Cleanup in Task 0**: Task 0 (or a kernel thread/workqueue) might have a pending operation (e.g., a delayed work item, timer, or interrupt handler) that references the freed memory. When the driver is removed, this pending operation is not canceled or synchronized. 2. **Component Framework Race**: The `component_bind_all`/`component_unbind_all` framework might not properly synchronize with all components. If one component (e.g., the HDMI encoder) has a pending operation that accesses resources from another component (e.g., the DRM master), a UAF can occur. 3. **Hardware Interrupt**: An interrupt from the HDMI controller
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