| Sažetak |
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. |
