Description

In the Linux kernel, the following vulnerability has been resolved: usb: dwc3: Fix race condition between concurrent dwc3_remove_requests() call paths This patch addresses a race condition caused by unsynchronized execution of multiple call paths invoking `dwc3_remove_requests()`, leading to premature freeing of USB requests and subsequent crashes. Three distinct execution paths interact with `dwc3_remove_requests()`: Path 1: Triggered via `dwc3_gadget_reset_interrupt()` during USB reset handling. The call stack includes: - `dwc3_ep0_reset_state()` - `dwc3_ep0_stall_and_restart()` - `dwc3_ep0_out_start()` - `dwc3_remove_requests()` - `dwc3_gadget_del_and_unmap_request()` Path 2: Also initiated from `dwc3_gadget_reset_interrupt()`, but through `dwc3_stop_active_transfers()`. The call stack includes: - `dwc3_stop_active_transfers()` - `dwc3_remove_requests()` - `dwc3_gadget_del_and_unmap_request()` Path 3: Occurs independently during `adb root` execution, which triggers USB function unbind and bind operations. The sequence includes: - `gserial_disconnect()` - `usb_ep_disable()` - `dwc3_gadget_ep_disable()` - `dwc3_remove_requests()` with `-ESHUTDOWN` status Path 3 operates asynchronously and lacks synchronization with Paths 1 and 2. When Path 3 completes, it disables endpoints and frees 'out' requests. If Paths 1 or 2 are still processing these requests, accessing freed memory leads to a crash due to use-after-free conditions. To fix this added check for request completion and skip processing if already completed and added the request status for ep0 while queue.

References 7

• git.kernel.org https://git.kernel.org/stable/c/467add9db13219101f14b6cc5477998b4aaa5fe2
• git.kernel.org https://git.kernel.org/stable/c/47de14d741cc4057046c9e2f33df1f7828254e6c
• git.kernel.org https://git.kernel.org/stable/c/67192e8cb7f941b5bba91e4bb290683576ce1607
• git.kernel.org https://git.kernel.org/stable/c/7cfb62888eba292fa35cd9ddbd28ce595f60e139
• git.kernel.org https://git.kernel.org/stable/c/afc0e34f161ce61ad351303c46eb57bd44b8b090
• git.kernel.org https://git.kernel.org/stable/c/e4037689a366743c4233966f0e74bc455820d316
• git.kernel.org https://git.kernel.org/stable/c/fa5eaf701e576880070b60922200557ae4aa54e1

Remediation