The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From b81ac4395bbeaf36e078dea1a48c02dd97b76235 Mon Sep 17 00:00:00 2001 From: Dan Vacura w36195@motorola.com Date: Tue, 3 May 2022 15:10:38 -0500 Subject: [PATCH] usb: gadget: uvc: allow for application to cleanly shutdown

Several types of kernel panics can occur due to timing during the uvc gadget removal. This appears to be a problem with gadget resources being managed by both the client application's v4l2 open/close and the UDC gadget bind/unbind. Since the concept of USB_GADGET_DELAYED_STATUS doesn't exist for unbind, add a wait to allow for the application to close out.

Some examples of the panics that can occur are:

<1>[ 1147.652313] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000028 <4>[ 1147.652510] Call trace: <4>[ 1147.652514] usb_gadget_disconnect+0x74/0x1f0 <4>[ 1147.652516] usb_gadget_deactivate+0x38/0x168 <4>[ 1147.652520] usb_function_deactivate+0x54/0x90 <4>[ 1147.652524] uvc_function_disconnect+0x14/0x38 <4>[ 1147.652527] uvc_v4l2_release+0x34/0xa0 <4>[ 1147.652537] __fput+0xdc/0x2c0 <4>[ 1147.652540] ____fput+0x10/0x1c <4>[ 1147.652545] task_work_run+0xe4/0x12c <4>[ 1147.652549] do_notify_resume+0x108/0x168

<1>[ 282.950561][ T1472] Unable to handle kernel NULL pointer dereference at virtual address 00000000000005b8 <6>[ 282.953111][ T1472] Call trace: <6>[ 282.953121][ T1472] usb_function_deactivate+0x54/0xd4 <6>[ 282.953134][ T1472] uvc_v4l2_release+0xac/0x1e4 <6>[ 282.953145][ T1472] v4l2_release+0x134/0x1f0 <6>[ 282.953167][ T1472] __fput+0xf4/0x428 <6>[ 282.953178][ T1472] ____fput+0x14/0x24 <6>[ 282.953193][ T1472] task_work_run+0xac/0x130

<3>[ 213.410077][ T29] configfs-gadget gadget: uvc: Failed to queue request (-108). <1>[ 213.410116][ T29] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000003 <6>[ 213.413460][ T29] Call trace: <6>[ 213.413474][ T29] uvcg_video_pump+0x1f0/0x384 <6>[ 213.413489][ T29] process_one_work+0x2a4/0x544 <6>[ 213.413502][ T29] worker_thread+0x350/0x784 <6>[ 213.413515][ T29] kthread+0x2ac/0x320 <6>[ 213.413528][ T29] ret_from_fork+0x10/0x30

Signed-off-by: Dan Vacura w36195@motorola.com Cc: stable stable@vger.kernel.org Link: https://lore.kernel.org/r/20220503201039.71720-1-w36195@motorola.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.c index 71bb5e477dba..d37965867b23 100644 --- a/drivers/usb/gadget/function/f_uvc.c +++ b/drivers/usb/gadget/function/f_uvc.c @@ -890,13 +890,37 @@ static void uvc_function_unbind(struct usb_configuration *c, { struct usb_composite_dev *cdev = c->cdev; struct uvc_device *uvc = to_uvc(f); + long wait_ret = 1;

uvcg_info(f, "%s()\n", __func__);

+ /* If we know we're connected via v4l2, then there should be a cleanup + * of the device from userspace either via UVC_EVENT_DISCONNECT or + * though the video device removal uevent. Allow some time for the + * application to close out before things get deleted. + */ + if (uvc->func_connected) { + uvcg_dbg(f, "waiting for clean disconnect\n"); + wait_ret = wait_event_interruptible_timeout(uvc->func_connected_queue, + uvc->func_connected == false, msecs_to_jiffies(500)); + uvcg_dbg(f, "done waiting with ret: %ld\n", wait_ret); + } + device_remove_file(&uvc->vdev.dev, &dev_attr_function_name); video_unregister_device(&uvc->vdev); v4l2_device_unregister(&uvc->v4l2_dev);

+ if (uvc->func_connected) { + /* Wait for the release to occur to ensure there are no longer any + * pending operations that may cause panics when resources are cleaned + * up. + */ + uvcg_warn(f, "%s no clean disconnect, wait for release\n", __func__); + wait_ret = wait_event_interruptible_timeout(uvc->func_connected_queue, + uvc->func_connected == false, msecs_to_jiffies(1000)); + uvcg_dbg(f, "done waiting for release with ret: %ld\n", wait_ret); + } + usb_ep_free_request(cdev->gadget->ep0, uvc->control_req); kfree(uvc->control_buf);

@@ -915,6 +939,7 @@ static struct usb_function *uvc_alloc(struct usb_function_instance *fi)

mutex_init(&uvc->video.mutex); uvc->state = UVC_STATE_DISCONNECTED; + init_waitqueue_head(&uvc->func_connected_queue); opts = fi_to_f_uvc_opts(fi);

mutex_lock(&opts->lock); diff --git a/drivers/usb/gadget/function/uvc.h b/drivers/usb/gadget/function/uvc.h index c3607a32b986..886103a1fe9b 100644 --- a/drivers/usb/gadget/function/uvc.h +++ b/drivers/usb/gadget/function/uvc.h @@ -14,6 +14,7 @@ #include <linux/spinlock.h> #include <linux/usb/composite.h> #include <linux/videodev2.h> +#include <linux/wait.h>

#include <media/v4l2-device.h> #include <media/v4l2-dev.h> @@ -129,6 +130,7 @@ struct uvc_device { struct usb_function func; struct uvc_video video; bool func_connected; + wait_queue_head_t func_connected_queue;

/* Descriptors */ struct { diff --git a/drivers/usb/gadget/function/uvc_v4l2.c b/drivers/usb/gadget/function/uvc_v4l2.c index a2c78690c5c2..fd8f73bb726d 100644 --- a/drivers/usb/gadget/function/uvc_v4l2.c +++ b/drivers/usb/gadget/function/uvc_v4l2.c @@ -253,10 +253,11 @@ uvc_v4l2_subscribe_event(struct v4l2_fh *fh,

static void uvc_v4l2_disable(struct uvc_device *uvc) { - uvc->func_connected = false; uvc_function_disconnect(uvc); uvcg_video_enable(&uvc->video, 0); uvcg_free_buffers(&uvc->video.queue); + uvc->func_connected = false; + wake_up_interruptible(&uvc->func_connected_queue); }

static int