On 17.1.2020 9.41, Macpaul Lin wrote:
According to NULL pointer fix: https://tinyurl.com/uqft5ra
xhci: Fix NULL pointer dereference with xhci_irq() for shared_hcd
The similar issue has also been found in QC activities in Mediatek.
Here quote the description from the referenced patch as follows.
"Commit ("f068090426ea xhci: Fix leaking USB3 shared_hcd
at xhci removal") sets xhci_shared_hcd to NULL without
stopping xhci host. This results into a race condition
where shared_hcd (super speed roothub) related interrupts
are being handled with xhci_irq happens when the
xhci_plat_remove is called and shared_hcd is set to NULL.
Fix this by setting the shared_hcd to NULL only after the
controller is halted and no interrupts are generated."
Signed-off-by: Sriharsha Allenki <sallenki@xxxxxxxxxxxxxx>
Signed-off-by: Macpaul Lin <macpaul.lin@xxxxxxxxxxxx>
---
drivers/usb/host/xhci-mtk.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/usb/host/xhci-mtk.c b/drivers/usb/host/xhci-mtk.c
index b18a6baef204..c227c67f5dc5 100644
--- a/drivers/usb/host/xhci-mtk.c
+++ b/drivers/usb/host/xhci-mtk.c
@@ -593,11 +593,11 @@ static int xhci_mtk_remove(struct platform_device *dev)
struct usb_hcd *shared_hcd = xhci->shared_hcd;
usb_remove_hcd(shared_hcd);
- xhci->shared_hcd = NULL;
device_init_wakeup(&dev->dev, false);
usb_remove_hcd(hcd);
usb_put_hcd(shared_hcd);
+ xhci->shared_hcd = NULL;
usb_put_hcd(hcd);
xhci_mtk_sch_exit(mtk);
xhci_mtk_clks_disable(mtk);
Could you share details of the NULL pointer dereference, (backtrace).
The USB3 hcd is already removed when xhci->shared_hcd is set to NULL.
We might want to add some checks to make sure we are not using the removed
hcd anymore in that codepath anymore.
-Mathias
