From: Wesley Cheng quic_wcheng@quicinc.com
[ Upstream commit bf594d1d0c1d7b895954018043536ffd327844f9 ]
The list_for_each_entry_safe() macro saves the current item (n) and the item after (n+1), so that n can be safely removed without corrupting the list. However, when traversing the list and removing items using gadget giveback, the DWC3 lock is briefly released, allowing other routines to execute. There is a situation where, while items are being removed from the cancelled_list using dwc3_gadget_ep_cleanup_cancelled_requests(), the pullup disable routine is running in parallel (due to UDC unbind). As the cleanup routine removes n, and the pullup disable removes n+1, once the cleanup retakes the DWC3 lock, it references a request who was already removed/handled. With list debug enabled, this leads to a panic. Ensure all instances of the macro are replaced where gadget giveback is used.
Example call stack:
Thread#1: __dwc3_gadget_ep_set_halt() - CLEAR HALT -> dwc3_gadget_ep_cleanup_cancelled_requests() ->list_for_each_entry_safe() ->dwc3_gadget_giveback(n) ->dwc3_gadget_del_and_unmap_request()- n deleted[cancelled_list] ->spin_unlock ->Thread#2 executes ... ->dwc3_gadget_giveback(n+1) ->Already removed!
Thread#2: dwc3_gadget_pullup() ->waiting for dwc3 spin_lock ... ->Thread#1 released lock ->dwc3_stop_active_transfers() ->dwc3_remove_requests() ->fetches n+1 item from cancelled_list (n removed by Thread#1) ->dwc3_gadget_giveback() ->dwc3_gadget_del_and_unmap_request()- n+1 deleted[cancelled_list] ->spin_unlock
Fixes: d4f1afe5e896 ("usb: dwc3: gadget: move requests to cancelled_list") Signed-off-by: Wesley Cheng quic_wcheng@quicinc.com Link: https://lore.kernel.org/r/20220414183521.23451-1-quic_wcheng@quicinc.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/usb/dwc3/gadget.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-)
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index 78ec6af79c7f..5c1ae0d0ed47 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -1978,10 +1978,10 @@ static void dwc3_gadget_ep_skip_trbs(struct dwc3_ep *dep, struct dwc3_request *r static void dwc3_gadget_ep_cleanup_cancelled_requests(struct dwc3_ep *dep) { struct dwc3_request *req; - struct dwc3_request *tmp; struct dwc3 *dwc = dep->dwc;
- list_for_each_entry_safe(req, tmp, &dep->cancelled_list, list) { + while (!list_empty(&dep->cancelled_list)) { + req = next_request(&dep->cancelled_list); dwc3_gadget_ep_skip_trbs(dep, req); switch (req->status) { case DWC3_REQUEST_STATUS_DISCONNECTED: @@ -1998,6 +1998,12 @@ static void dwc3_gadget_ep_cleanup_cancelled_requests(struct dwc3_ep *dep) dwc3_gadget_giveback(dep, req, -ECONNRESET); break; } + /* + * The endpoint is disabled, let the dwc3_remove_requests() + * handle the cleanup. + */ + if (!dep->endpoint.desc) + break; } }
@@ -3288,15 +3294,21 @@ static void dwc3_gadget_ep_cleanup_completed_requests(struct dwc3_ep *dep, const struct dwc3_event_depevt *event, int status) { struct dwc3_request *req; - struct dwc3_request *tmp;
- list_for_each_entry_safe(req, tmp, &dep->started_list, list) { + while (!list_empty(&dep->started_list)) { int ret;
+ req = next_request(&dep->started_list); ret = dwc3_gadget_ep_cleanup_completed_request(dep, event, req, status); if (ret) break; + /* + * The endpoint is disabled, let the dwc3_remove_requests() + * handle the cleanup. + */ + if (!dep->endpoint.desc) + break; } }