From: Mathias Nyman mathias.nyman@linux.intel.com
commit 6ae6dc22d2d1ce6aa77a6da8a761e61aca216f8b upstream.
xHC hardware can only have one slot in default state with address 0 waiting for a unique address at a time, otherwise "undefined behavior may occur" according to xhci spec 5.4.3.4
The address0_mutex exists to prevent this across both xhci roothubs.
If hub_port_init() fails, it may unlock the mutex and exit with a xhci slot in default state. If the other xhci roothub calls hub_port_init() at this point we end up with two slots in default state.
Make sure the address0_mutex protects the slot default state across hub_port_init() retries, until slot is addressed or disabled.
Note, one known minor case is not fixed by this patch. If device needs to be reset during resume, but fails all hub_port_init() retries in usb_reset_and_verify_device(), then it's possible the slot is still left in default state when address0_mutex is unlocked.
Cc: stable@vger.kernel.org Fixes: 638139eb95d2 ("usb: hub: allow to process more usb hub events in parallel") Signed-off-by: Mathias Nyman mathias.nyman@linux.intel.com Link: https://lore.kernel.org/r/20211115221630.871204-1-mathias.nyman@linux.intel.... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/core/hub.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-)
--- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -4628,8 +4628,6 @@ hub_port_init(struct usb_hub *hub, struc if (oldspeed == USB_SPEED_LOW) delay = HUB_LONG_RESET_TIME;
- mutex_lock(hcd->address0_mutex); - /* Reset the device; full speed may morph to high speed */ /* FIXME a USB 2.0 device may morph into SuperSpeed on reset. */ retval = hub_port_reset(hub, port1, udev, delay, false); @@ -4940,7 +4938,6 @@ fail: hub_port_disable(hub, port1, 0); update_devnum(udev, devnum); /* for disconnect processing */ } - mutex_unlock(hcd->address0_mutex); return retval; }
@@ -5170,6 +5167,9 @@ static void hub_port_connect(struct usb_ unit_load = 100;
status = 0; + + mutex_lock(hcd->address0_mutex); + for (i = 0; i < PORT_INIT_TRIES; i++) {
/* reallocate for each attempt, since references @@ -5206,6 +5206,8 @@ static void hub_port_connect(struct usb_ if (status < 0) goto loop;
+ mutex_unlock(hcd->address0_mutex); + if (udev->quirks & USB_QUIRK_DELAY_INIT) msleep(2000);
@@ -5294,6 +5296,7 @@ static void hub_port_connect(struct usb_
loop_disable: hub_port_disable(hub, port1, 1); + mutex_lock(hcd->address0_mutex); loop: usb_ep0_reinit(udev); release_devnum(udev); @@ -5320,6 +5323,8 @@ loop: }
done: + mutex_unlock(hcd->address0_mutex); + hub_port_disable(hub, port1, 1); if (hcd->driver->relinquish_port && !hub->hdev->parent) { if (status != -ENOTCONN && status != -ENODEV) @@ -5839,6 +5844,8 @@ static int usb_reset_and_verify_device(s bos = udev->bos; udev->bos = NULL;
+ mutex_lock(hcd->address0_mutex); + for (i = 0; i < PORT_INIT_TRIES; ++i) {
/* ep0 maxpacket size may change; let the HCD know about it. @@ -5848,6 +5855,7 @@ static int usb_reset_and_verify_device(s if (ret >= 0 || ret == -ENOTCONN || ret == -ENODEV) break; } + mutex_unlock(hcd->address0_mutex);
if (ret < 0) goto re_enumerate;