6.6-stable review patch. If anyone has any objections, please let me know.
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From: Manish Nagar manish.nagar@oss.qualcomm.com
commit e4037689a366743c4233966f0e74bc455820d316 upstream.
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.
Fixes: 72246da40f37 ("usb: Introduce DesignWare USB3 DRD Driver") Cc: stable stable@kernel.org Suggested-by: Thinh Nguyen Thinh.Nguyen@synopsys.com Acked-by: Thinh Nguyen Thinh.Nguyen@synopsys.com Signed-off-by: Manish Nagar manish.nagar@oss.qualcomm.com Link: https://patch.msgid.link/20251120074435.1983091-1-manish.nagar@oss.qualcomm.... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/dwc3/ep0.c | 1 + drivers/usb/dwc3/gadget.c | 7 +++++++ 2 files changed, 8 insertions(+)
--- a/drivers/usb/dwc3/ep0.c +++ b/drivers/usb/dwc3/ep0.c @@ -94,6 +94,7 @@ static int __dwc3_gadget_ep0_queue(struc req->request.actual = 0; req->request.status = -EINPROGRESS; req->epnum = dep->number; + req->status = DWC3_REQUEST_STATUS_QUEUED;
list_add_tail(&req->list, &dep->pending_list);
--- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -229,6 +229,13 @@ void dwc3_gadget_giveback(struct dwc3_ep { struct dwc3 *dwc = dep->dwc;
+ /* + * The request might have been processed and completed while the + * spinlock was released. Skip processing if already completed. + */ + if (req->status == DWC3_REQUEST_STATUS_COMPLETED) + return; + dwc3_gadget_del_and_unmap_request(dep, req, status); req->status = DWC3_REQUEST_STATUS_COMPLETED;