usb: free iso schedules on failed submit

usb: free iso schedules on failed submit

EHCI and FOTG210 isochronous submits build an ehci_iso_sched before
linking the URB to the endpoint queue, and keep the staged schedule in
urb->hcpriv until iso_stream_schedule() and the link helpers consume it.
If the controller is no longer accessible, or usb_hcd_link_urb_to_ep()
fails, submit jumps to done_not_linked before that handoff happens and
leaks the staged schedule still attached to urb->hcpriv.

Free the staged schedule from done_not_linked when submit fails before
the URB is linked and clear urb->hcpriv after the free.

The bug was first flagged by an experimental analysis tool we are
developing for kernel memory-management bugs while analyzing
v6.13-rc1. The tool is still under development and is not yet publicly
available. Manual inspection confirms that the bug is still
present in v7.1.1.

An x86_64 allyesconfig build showed no new warnings. As we do not have an
EHCI host controller with a USB isochronous device to test with, no
runtime testing was able to be performed.

Fixes: 8de98402652c ("[PATCH] USB: Fix USB suspend/resume crasher (#2)")
Fixes: e9df41c5c589 ("USB: make HCDs responsible for managing endpoint queues")
Fixes: 7d50195f6c50 ("usb: host: Faraday fotg210-hcd driver")
Cc: stable <stable@kernel.org>
Signed-off-by: Dawei Feng <dawei.feng@seu.edu.cn>
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://patch.msgid.link/20260630071419.349161-1-dawei.feng@seu.edu.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>