[PATCH 1/1] xhci: Fix Panther point NULL pointer deref at full-speed re-enumeration

[Mathias Nyman <mathias.nyman@linux.intel.com>]

re-enumerating full-speed devices after a failed address device command
can trigger a NULL pointer dereference.

Full-speed devices may need to reconfigure the endpoint 0 Max Packet Size
value during enumeration. Usb core calls usb_ep0_reinit() in this case,
which ends up calling xhci_configure_endpoint().

On Panther point xHC the xhci_configure_endpoint() function will
additionally check and reserve bandwidth in software. Other hosts do
this in hardware

If xHC address device command fails then a new xhci_virt_device structure
is allocated as part of re-enabling the slot, but the bandwidth table
pointers are not set up properly here.
This triggers the NULL pointer dereference the next time usb_ep0_reinit()
is called and xhci_configure_endpoint() tries to check and reserve
bandwidth

[46710.713538] usb 3-1: new full-speed USB device number 5 using xhci_hcd
[46710.713699] usb 3-1: Device not responding to setup address.
[46710.917684] usb 3-1: Device not responding to setup address.
[46711.125536] usb 3-1: device not accepting address 5, error -71
[46711.125594] BUG: kernel NULL pointer dereference, address: 0000000000000008
[46711.125600] #PF: supervisor read access in kernel mode
[46711.125603] #PF: error_code(0x0000) - not-present page
[46711.125606] PGD 0 P4D 0
[46711.125610] Oops: Oops: 0000 [#1] PREEMPT SMP PTI
[46711.125615] CPU: 1 PID: 25760 Comm: kworker/1:2 Not tainted 6.10.3_2 #1
[46711.125620] Hardware name: Gigabyte Technology Co., Ltd.
[46711.125623] Workqueue: usb_hub_wq hub_event [usbcore]
[46711.125668] RIP: 0010:xhci_reserve_bandwidth (drivers/usb/host/xhci.c

Fix this by making sure bandwidth table pointers are set up correctly
after a failed address device command, and additionally by avoiding
checking for bandwidth in cases like this where no actual endpoints are
added or removed, i.e. only context for default control endpoint 0 is
evaluated.

Reported-by: Karel Balej <balejk@matfyz.cz>
Closes: https://lore.kernel.org/linux-usb/D3CKQQAETH47.1MUO22RTCH2O3@matfyz.cz/
Cc: stable@vger.kernel.org
Fixes: 651aaf36a7d7 ("usb: xhci: Handle USB transaction error on address command")
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
---
 drivers/usb/host/xhci.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 0a8cf6c17f82..efdf4c228b8c 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -2837,7 +2837,7 @@ static int xhci_configure_endpoint(struct xhci_hcd *xhci,
 				xhci->num_active_eps);
 		return -ENOMEM;
 	}
-	if ((xhci->quirks & XHCI_SW_BW_CHECKING) &&
+	if ((xhci->quirks & XHCI_SW_BW_CHECKING) && !ctx_change &&
 	    xhci_reserve_bandwidth(xhci, virt_dev, command->in_ctx)) {
 		if ((xhci->quirks & XHCI_EP_LIMIT_QUIRK))
 			xhci_free_host_resources(xhci, ctrl_ctx);
@@ -4200,8 +4200,10 @@ static int xhci_setup_device(struct usb_hcd *hcd, struct usb_device *udev,
 		mutex_unlock(&xhci->mutex);
 		ret = xhci_disable_slot(xhci, udev->slot_id);
 		xhci_free_virt_device(xhci, udev->slot_id);
-		if (!ret)
-			xhci_alloc_dev(hcd, udev);
+		if (!ret) {
+			if (xhci_alloc_dev(hcd, udev) == 1)
+				xhci_setup_addressable_virt_dev(xhci, udev);
+		}
 		kfree(command->completion);
 		kfree(command);
 		return -EPROTO;
-- 
2.25.1