جزئیات آسیب‌پذیری

In the Linux kernel, the following vulnerability has been resolved: Revert "media: v4l2-dev: fix error handling in __video_register_device()" This reverts commit 2a934fdb01db6458288fc9386d3d8ceba6dd551a. The intentions of that patch were good, but it doesn't work. The idea is that if device_register fails, you have to do a put_device to let the ref counter release resources. However, the V4L2 API says that if video_register_device() fails, then you have to call video_device_release(), which kfree()s the video_device struct. But the put_device() will already have freed the struct, so you end up in a double-free scenario. There is not really a good way of fixing this without breaking video_register_device() into two parts, one that initializes everything, and one that does the actual device_register, and then converting all V4L2 drivers to this new model. That is a massive job, and it is very unlikely that device_register will fail. So rather than ending up in a double-free scenario, just revert this patch, and in that case we'll have a small memory leak. Which is a lot more robust.

• https://git.kernel.org/stable/c/8b998c171ed875e402e1fd1c5cd619e4ca05e9c1
• https://git.kernel.org/stable/c/3de14b4f681a1b3c6d375d98d9d37a55ebb85349
• https://git.kernel.org/stable/c/8027f82c0f5474ed72448e160ee9778051fa1f49
• https://git.kernel.org/stable/c/2ac009a65d2385e9f0799eaf9d9694a29153a161
• https://git.kernel.org/stable/c/712ca1cf756de2557a116e0df55791bac0c9f99e
• https://git.kernel.org/stable/c/aad08b5f67d2a8116e1a00bce2611c1513b10bce
• https://git.kernel.org/stable/c/ce792b94e03882108019ba996c1a7c4d4e09be2c
• https://git.kernel.org/stable/c/e7600f5cee5de14065f950807931d6e6d40fb2d7