Bug 219481

Created attachment 307171 [details]
Bug: A buffer overflow vulnerability in the Bluetooth subsystem.   Location: drivers/bluetooth/btusb.c      This is Code with bug

Bug Report: Buffer Overflow Vulnerability in `btusb_write` Function
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Summary:
A buffer overflow vulnerability has been identified in the `btusb_write` function within the Bluetooth subsystem of the Linux kernel (`drivers/bluetooth/btusb.c`). The function does not properly validate the size of the data being written, which may lead to a potential buffer overflow.
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Location:
- File: `drivers/bluetooth/btusb.c`
- Function: `btusb_write`
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Description:
The current implementation of the `btusb_write` function performs a check to ensure that the `count` (number of bytes to write) does not exceed 64 bytes. However, it does not perform any additional validation to ensure that the `count` value is a positive integer. This can lead to unexpected behavior, including potential buffer overflow, if the `count` is zero or negative.
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Issue:
- The check `if (count > 64)` ensures that the count does not exceed 64 bytes, but it does not validate that `count` is a positive number.
- If `count` is zero or negative, the behavior is undefined, potentially leading to a buffer overflow, memory corruption, or other unexpected behavior.
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Proposed Fix:
Add an additional check to ensure that `count` is greater than zero before proceeding with the write operation. This will prevent the possibility of passing an invalid `count` value (i.e., zero or negative).
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Explanation:
- The additional condition `if (count <= 0)` ensures that the write operation will not proceed if the `count` is zero or negative, which could have resulted in an invalid memory access or other undefined behavior.
- This fix improves the robustness of the function by properly validating the `count` value before using it in the `btusb_submit_cmd` function.
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Impact:
This bug could potentially lead to security vulnerabilities or crashes if negative or zero values are passed to the `btusb_write` function. The proposed fix mitigates the risk of buffer overflows by ensuring that only valid sizes are used for data writing operations.
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Steps to Reproduce:
1. Clone the Linux kernel source code (`git clone https://github.com/torvalds/linux.git`).
2. Locate the function `btusb_write` in `drivers/bluetooth/btusb.c`.
3. Provide an invalid value (e.g., zero or negative) for `count` when calling the function.
4. Observe that the function may fail to handle the invalid size appropriately, potentially causing undefined behavior.
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Patch Available:  
Yes. A patch has been proposed in the "Corrected Code" section above.
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Additional Notes:
This issue was identified using static analysis tools, but it may not have been readily apparent during regular testing or use. It's recommended that this bug be fixed to ensure the stability and security of the Bluetooth subsystem.