3c5880745b
When dwc3_gadget_ep_cleanup_completed_requests() called to
dwc3_gadget_giveback() where the dwc3 lock is released, other thread is
able to execute. In this situation, usb_ep_disable() gets the chance to
clear endpoint descriptor pointer which leds to the null pointer
dereference problem. So needs to move the null pointer check to a proper
place.
Example call stack:
Thread#1:
dwc3_thread_interrupt()
spin_lock
-> dwc3_process_event_buf()
-> dwc3_process_event_entry()
-> dwc3_endpoint_interrupt()
-> dwc3_gadget_endpoint_trbs_complete()
-> dwc3_gadget_ep_cleanup_completed_requests()
...
-> dwc3_giveback()
spin_unlock
Thread#2 executes
Thread#2:
configfs_composite_disconnect()
-> __composite_disconnect()
-> ffs_func_disable()
-> ffs_func_set_alt()
-> ffs_func_eps_disable()
-> usb_ep_disable()
wait for dwc3 spin_lock
Thread#1 released lock
clear endpoint.desc
Fixes: 26288448120b ("usb: dwc3: gadget: Fix null pointer exception")
Cc: stable <stable@kernel.org>
Signed-off-by: Albert Wang <albertccwang@google.com>
Link: https://lore.kernel.org/r/20220518061315.3359198-1-albertccwang@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.