This is a note to let you know that I've just added the patch titled
usb: dwc3: gadget: Replace list_for_each_entry_safe() if using giveback
to the 5.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
usb-dwc3-gadget-replace-list_for_each_entry_safe-if-.patch
and it can be found in the queue-5.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 0902764162a997c2c69a5a5cac151835879e8f3b
Author: Wesley Cheng <quic_wcheng@xxxxxxxxxxx>
Date: Thu Apr 14 11:35:21 2022 -0700
usb: dwc3: gadget: Replace list_for_each_entry_safe() if using giveback
[ 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@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220414183521.23451-1-quic_wcheng@xxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 026fc360cc50..6936d8ce8981 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2001,10 +2001,10 @@ 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:
@@ -2021,6 +2021,12 @@ 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;
}
}
@@ -3333,15 +3339,21 @@ 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;
}
}
