From: Wesley Cheng wcheng@codeaurora.org
commit d25d85061bd856d6be221626605319154f9b5043 upstream.
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
Fix this condition by utilizing list_replace_init(), and traversing through a local copy of the current elements in the endpoint lists. This will also set the parent list as empty, so if another thread is also looping through the list, it will be empty on the next iteration.
Fixes: d4f1afe5e896 ("usb: dwc3: gadget: move requests to cancelled_list") Cc: stable stable@vger.kernel.org Acked-by: Felipe Balbi balbi@kernel.org Signed-off-by: Wesley Cheng wcheng@codeaurora.org Link: https://lore.kernel.org/r/1627543994-20327-1-git-send-email-wcheng@codeauror... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/dwc3/gadget.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-)
--- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -1741,9 +1741,13 @@ static void dwc3_gadget_ep_cleanup_cance { struct dwc3_request *req; struct dwc3_request *tmp; + struct list_head local; struct dwc3 *dwc = dep->dwc;
- list_for_each_entry_safe(req, tmp, &dep->cancelled_list, list) { +restart: + list_replace_init(&dep->cancelled_list, &local); + + list_for_each_entry_safe(req, tmp, &local, list) { dwc3_gadget_ep_skip_trbs(dep, req); switch (req->status) { case DWC3_REQUEST_STATUS_DISCONNECTED: @@ -1761,6 +1765,9 @@ static void dwc3_gadget_ep_cleanup_cance break; } } + + if (!list_empty(&dep->cancelled_list)) + goto restart; }
static int dwc3_gadget_ep_dequeue(struct usb_ep *ep, @@ -2945,8 +2952,12 @@ static void dwc3_gadget_ep_cleanup_compl { struct dwc3_request *req; struct dwc3_request *tmp; + struct list_head local;
- list_for_each_entry_safe(req, tmp, &dep->started_list, list) { +restart: + list_replace_init(&dep->started_list, &local); + + list_for_each_entry_safe(req, tmp, &local, list) { int ret;
ret = dwc3_gadget_ep_cleanup_completed_request(dep, event, @@ -2954,6 +2965,9 @@ static void dwc3_gadget_ep_cleanup_compl if (ret) break; } + + if (!list_empty(&dep->started_list)) + goto restart; }
static bool dwc3_gadget_ep_should_continue(struct dwc3_ep *dep)