The crash appears in the following situations:
1. Call usb_ep_dequeue without calling usb_ep_queue first
2. Repeated call usb_ep_dequeue
Below is the log of kernel crash when stopping USB FFS device:
[ 1044.732419] Unable to handle kernel NULL pointer dereference
at virtual address 0000000000000000
...
[ 1044.946689] Call trace:
[ 1044.949133] cdnsp_trb_in_td.constprop.0+0x4/0xd0 [cdns3]
[ 1044.954545] cdnsp_gadget_ep_dequeue+0x88/0xf0 [cdns3]
[ 1044.959695] usb_ep_dequeue+0x18/0x24
[ 1044.963366] functionfs_unbind+0x2c/0xb4 [usb_f_fs]
[ 1044.968256] ffs_func_unbind+0x110/0x124 [usb_f_fs]
[ 1044.973144] purge_configs_funcs+0x9c/0x124 [libcomposite]
[ 1044.978646] configfs_composite_unbind+0x5c/0xbc [libcomposite]
[ 1044.984581] usb_gadget_remove_driver+0x60/0xf4
[ 1044.989120] usb_gadget_unregister_driver+0x70/0xe4
[ 1044.994008] unregister_gadget_item+0x30/0x58 [libcomposite]
[ 1044.999682] ffs_data_clear+0x144/0x158 [usb_f_fs]
[ 1045.004483] ffs_data_closed+0xdc/0x174 [usb_f_fs]
[ 1045.009283] ffs_ep0_release+0x14/0x24 [usb_f_fs]
Signed-off-by: Jing Leng <3090101217@xxxxxxxxxx>
---
drivers/usb/cdns3/cdnsp-gadget.c | 11 +++++++++--
drivers/usb/cdns3/cdnsp-ring.c | 5 +++++
2 files changed, 14 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/cdns3/cdnsp-gadget.c b/drivers/usb/cdns3/cdnsp-gadget.c
index fff9ec9c391f..160680a56e1d 100644
--- a/drivers/usb/cdns3/cdnsp-gadget.c
+++ b/drivers/usb/cdns3/cdnsp-gadget.c
@@ -1072,6 +1072,7 @@ static struct usb_request *cdnsp_gadget_ep_alloc_request(struct usb_ep *ep,
preq->epnum = pep->number;
preq->pep = pep;
+ INIT_LIST_HEAD(&preq->td.td_list);
trace_cdnsp_alloc_request(preq);
@@ -1120,11 +1121,17 @@ static int cdnsp_gadget_ep_queue(struct usb_ep *ep,
static int cdnsp_gadget_ep_dequeue(struct usb_ep *ep,
struct usb_request *request)
{
- struct cdnsp_ep *pep = to_cdnsp_ep(ep);
- struct cdnsp_device *pdev = pep->pdev;
+ struct cdnsp_ep *pep;
+ struct cdnsp_device *pdev;
unsigned long flags;
int ret;
+ if (!request || !ep)
+ return -EINVAL;
+
+ pep = to_cdnsp_ep(ep);
+ pdev = pep->pdev;
+
if (!pep->endpoint.desc) {
dev_err(pdev->dev,
"%s: can't dequeue to disabled endpoint\n",
diff --git a/drivers/usb/cdns3/cdnsp-ring.c b/drivers/usb/cdns3/cdnsp-ring.c
index 07f6068342d4..12dc3fb100e9 100644
--- a/drivers/usb/cdns3/cdnsp-ring.c
+++ b/drivers/usb/cdns3/cdnsp-ring.c
@@ -705,6 +705,11 @@ int cdnsp_remove_request(struct cdnsp_device *pdev,
trace_cdnsp_remove_request_td(preq);
cur_td = &preq->td;
+
+ /* Prevent kernel crash caused by re-running usb_ep_dequeue */
+ if (list_empty(&cur_td->td_list))
+ return ret;
+
ep_ring = cdnsp_request_to_transfer_ring(pdev, preq);
/*
--
2.17.1
