CVE-2021-46976 in Linux
Sumário
de VulDB • 29/05/2026
Based on the kernel log snippet provided, here is an analysis of the crash and potential causes.
### **1. Summary of the Crash** * **Type:** Kernel Oops/Panic (indicated by `WARNING kernel` and the call trace). * **Timestamp:** `2021-04-24T18:03:53.804324Z` * **CPU State:** * `CR0: 0000000080050033` (Standard control register state) * `CR2: 0000239514955000` **← Critical: This is the faulting virtual address.** * `CR3: 00000007f82da001` (Page table base) * `CR4: 0000000000760ee0` * `PKRU: 55555554` (Protection Keys for Userspace) * **Faulting Address (`CR2`):** `0x239514955000` * This address is **not** a typical user-space address (which would be in the lower half of the address space on 64-bit systems) nor a standard kernel high-memory address. It looks like a **NULL pointer dereference** or an **invalid pointer** that was not properly initialized or was freed. * Specifically, `0x239514955000` is a very high address, suggesting it might be a **kernel pointer that was corrupted** or a **user pointer that was incorrectly accessed in kernel space** without proper `copy_from_user`/`copy_to_user` checks.
### **2. Call Trace Analysis** The crash occurred in the kernel workqueue subsystem:
``` __active_retire+0x77/0xcf process_one_work+0x1da/0x394 worker_thread+0x216/0x375 kthread+0x147/0x156 ret_from_fork+0x1f/0x40 ```
* **`__active_retire`**: This function is part of the **kernel workqueue** implementation. It handles retiring active work items. * **`process_one_work`**: Processes a single work item from the workqueue. * **`worker_thread`**: The kernel thread that processes work items.
**Conclusion:** The crash happened while the kernel was trying to **retire a work item** that was previously queued. This strongly suggests: 1. A **use-after-free** bug: The work item structure was freed while still being processed. 2. A **double-free** or **corrupted pointer**: The pointer to the work item became invalid. 3. A **race condition**: The work item was modified or freed by another context while this thread was processing it.
### **3. Likely Culprits** Given the modules loaded (see below), the crash is likely related to one of the following subsystems:
#### **A. Intel IPU6 (Image Processing Unit) Drivers** The log shows many `intel_ipu6_*` modules: * `intel_ipu6_psys` * `intel_ipu6_isys` * `ov2740`, `ov8856` (Camera sensors) * `v4l2_fwnode`, `videobuf2_*`
**Why?** * Camera drivers often use workqueues for asynchronous operations (e.g., streaming, power management, sensor initialization). * If a camera sensor is disconnected or reset while a work item is pending, it can lead to a use-after-free. * The `CR2` address `0x239514955000` might be a pointer to a `v4l2_subdev` or `ipu6` context that was freed.
#### **B. SoundWire / SOF (Sound Open Firmware) Drivers** Modules: * `snd_soc_sof_sdw` * `snd_sof_pci` * `soundwire_*`
**Why?** * SoundWire and SOF drivers also use workqueues for firmware loading, power management, and audio stream setup. * Similar race conditions can occur if the hardware is removed or reset.
#### **C. ChromeOS EC (Embedded Controller) Drivers** Modules: * `cros_ec_typec` *
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