The provided stack trace indicates an undefined behavior detected by the UndefinedBehaviorSanitizer (UBSAN) in your program. The issue is located at `../hw/usb/imx-usb-phy.c:93:17`. ### Key Points from the Trace: 1. **Undefined Behavior**: The error occurs due to undefined behavior in the code, specifically at the line `imx-usb-phy.c:93:17`. 2. **Call Stack**: - The stack trace shows a sequence of function calls leading to the error. - The top-level function is `LLVMFuzzerTestOneInput`, which suggests this is part of a fuzzing test case for your program. - Functions like `videzzo_qemu`, `dispatch_mmio_read`, and `qemu_readl` are involved, indicating that the issue might be related to QEMU or device emulation. 3. **Base Unit**: The base unit appears to be all zeros (`0x0000...0000`), which might indicate an uninitialized value or a null pointer being used. ### Possible Causes: - **Null Pointer Dereference**: Accessing memory using a null pointer is a common cause of undefined behavior. - **Invalid Memory Access**: Reading or writing to invalid memory addresses (e.g., out-of-bounds arrays). - **Uninitialized Variables**: Using uninitialized variables, which can lead to accessing indeterminate values. ### Recommendations: 1. **Check for Null Pointers**: - Review the code around `imx-usb-phy.c:93` to ensure that all pointers are properly initialized before use. 2. **Validate Memory Access**: - Ensure that any memory accesses (e.g., array indices, pointer arithmetic) are within valid bounds. 3. **Initialize Variables**: - Make sure all variables are properly initialized before they are used, especially in safety-critical or high-integrity contexts. ### Debugging Steps: 1. **Locate the Exact Line**: - Look at line 93 in `imx-usb-phy.c` to see what operation is causing the undefined behavior. 2. **Check Surrounding Code**: - Review the code around that line to understand the context and identify any potential issues (e.g., uninitialized variables, null pointers). 3. **Use a Debugger**: - Use GDB or similar tools to debug the program and pinpoint where the undefined behavior occurs. 4. **Add Sanitizer Checks**: - Enable additional sanitizers (e.g., address sanitizer for buffer overflows) to catch more issues during testing. ### Conclusion: The error indicates a critical issue in your code that needs to be addressed immediately to prevent crashes or incorrect behavior. Focus on the line `imx-usb-phy.c:93:17` and ensure all pointers and variables are properly initialized and validated before use.