Alan Stern 65dadb2bee USB: Gadget: core: Help prevent panic during UVC unconfigure ... Avichal Rakesh reported a kernel panic that occurred when the UVC gadget driver was removed from a gadget's configuration. The panic involves a somewhat complicated interaction between the kernel driver and a userspace component (as described in the Link tag below), but the analysis did make one thing clear: The Gadget core should accomodate gadget drivers calling usb_gadget_deactivate() as part of their unbind procedure. Currently this doesn't work. gadget_unbind_driver() calls driver->unbind() while holding the udc->connect_lock mutex, and usb_gadget_deactivate() attempts to acquire that mutex, which will result in a deadlock. The simple fix is for gadget_unbind_driver() to release the mutex when invoking the ->unbind() callback. There is no particular reason for it to be holding the mutex at that time, and the mutex isn't held while the ->bind() callback is invoked. So we'll drop the mutex before performing the unbind callback and reacquire it afterward. We'll also add a couple of comments to usb_gadget_activate() and usb_gadget_deactivate(). Because they run in process context they must not be called from a gadget driver's ->disconnect() callback, which (according to the kerneldoc for struct usb_gadget_driver in include/linux/usb/gadget.h) may run in interrupt context. This may help prevent similar bugs from arising in the future. Reported-and-tested-by: Avichal Rakesh <arakesh@google.com> Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Fixes: 286d9975a8 ("usb: gadget: udc: core: Prevent soft_connect_store() race") Link: https://lore.kernel.org/linux-usb/4d7aa3f4-22d9-9f5a-3d70-1bd7148ff4ba@google.com/ Cc: Badhri Jagan Sridharan <badhri@google.com> Cc: <stable@vger.kernel.org> Link: https://lore.kernel.org/r/48b2f1f1-0639-46bf-bbfc-98cb05a24914@rowland.harvard.edu Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2023-08-04 14:56:24 +02:00
..
function	USB: gadget: f_hid: make hidg_class a static const structure	2023-06-20 16:20:48 +02:00
legacy	USB: gadget: Fix the memory leak in raw_gadget driver	2023-07-25 17:43:23 +02:00
udc	USB: Gadget: core: Help prevent panic during UVC unconfigure	2023-08-04 14:56:24 +02:00
composite.c	usb: gadget: call usb_gadget_check_config() to verify UDC capability	2023-07-25 17:46:25 +02:00
config.c
configfs.c	usb: gadget: Properly configure the device for remote wakeup	2023-03-29 10:27:00 +02:00
configfs.h
epautoconf.c
functions.c
Kconfig	usb: uvc: move uvc_fmts and uvc_format_by_guid to own compile unit	2023-01-31 09:40:42 +01:00
Makefile
u_f.c
u_f.h
u_os_desc.h
usbstring.c