usb: gadget: uvc: Allocate uvc_requests one at a time

Currently, the uvc gadget driver allocates all uvc_requests as one array
and deallocates them all when the video stream stops. This includes
de-allocating all the usb_requests associated with those uvc_requests.
This can lead to use-after-free issues if any of those de-allocated
usb_requests were still owned by the usb controller.

This patch is 1 of 2 patches addressing the use-after-free issue.
Instead of bulk allocating all uvc_requests as an array, this patch
allocates uvc_requests one at a time, which should allows for similar
granularity when deallocating the uvc_requests. This patch has no
functional changes other than allocating each uvc_request separately,
and similarly freeing each of them separately.

Link: https://lore.kernel.org/7cd81649-2795-45b6-8c10-b7df1055020d@google.com
Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Reviewed-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Suggested-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Tested-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Signed-off-by: Avichal Rakesh <arakesh@google.com>
Link: https://lore.kernel.org/r/20231109004104.3467968-2-arakesh@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/gadget/function/uvc.h b/drivers/usb/gadget/function/uvc.h
index 989bc6b4e93d36ab4d7ab691855fc18cbbb33d5b..993694da0bbcd2a54b25f2660a26b14dbb5a0e39 100644 (file)
--- a/drivers/usb/gadget/function/uvc.h
+++ b/drivers/usb/gadget/function/uvc.h
@@ -81,6 +81,7 @@ struct uvc_request {
        struct sg_table sgt;
        u8 header[UVCG_REQUEST_HEADER_LEN];
        struct uvc_buffer *last_buf;
+       struct list_head list;
 };
 
 struct uvc_video {
@@ -102,7 +103,7 @@ struct uvc_video {
 
        /* Requests */
        unsigned int req_size;
-       struct uvc_request *ureq;
+       struct list_head ureqs; /* all uvc_requests allocated by uvc_video */
        struct list_head req_free;
        spinlock_t req_lock;
 

diff --git a/drivers/usb/gadget/function/uvc_video.c b/drivers/usb/gadget/function/uvc_video.c
index c334802ac0a43f332a20b5aacf116bc45fecfc08..1619f9664748d4a834d9cf6b65654116e2aadb6d 100644 (file)
--- a/drivers/usb/gadget/function/uvc_video.c
+++ b/drivers/usb/gadget/function/uvc_video.c
@@ -227,6 +227,24 @@ uvc_video_encode_isoc(struct usb_request *req, struct uvc_video *video,
  * Request handling
  */
 
+static void
+uvc_video_free_request(struct uvc_request *ureq, struct usb_ep *ep)
+{
+       sg_free_table(&ureq->sgt);
+       if (ureq->req && ep) {
+               usb_ep_free_request(ep, ureq->req);
+               ureq->req = NULL;
+       }
+
+       kfree(ureq->req_buffer);
+       ureq->req_buffer = NULL;
+
+       if (!list_empty(&ureq->list))
+               list_del_init(&ureq->list);
+
+       kfree(ureq);
+}
+
 static int uvcg_video_ep_queue(struct uvc_video *video, struct usb_request *req)
 {
        int ret;
@@ -293,27 +311,12 @@ uvc_video_complete(struct usb_ep *ep, struct usb_request *req)
 static int
 uvc_video_free_requests(struct uvc_video *video)
 {
-       unsigned int i;
-
-       if (video->ureq) {
-               for (i = 0; i < video->uvc_num_requests; ++i) {
-                       sg_free_table(&video->ureq[i].sgt);
+       struct uvc_request *ureq, *temp;
 
-                       if (video->ureq[i].req) {
-                               usb_ep_free_request(video->ep, video->ureq[i].req);
-                               video->ureq[i].req = NULL;
-                       }
-
-                       if (video->ureq[i].req_buffer) {
-                               kfree(video->ureq[i].req_buffer);
-                               video->ureq[i].req_buffer = NULL;
-                       }
-               }
-
-               kfree(video->ureq);
-               video->ureq = NULL;
-       }
+       list_for_each_entry_safe(ureq, temp, &video->ureqs, list)
+               uvc_video_free_request(ureq, video->ep);
 
+       INIT_LIST_HEAD(&video->ureqs);
        INIT_LIST_HEAD(&video->req_free);
        video->req_size = 0;
        return 0;
@@ -322,6 +325,7 @@ uvc_video_free_requests(struct uvc_video *video)
 static int
 uvc_video_alloc_requests(struct uvc_video *video)
 {
+       struct uvc_request *ureq;
        unsigned int req_size;
        unsigned int i;
        int ret = -ENOMEM;
@@ -332,29 +336,33 @@ uvc_video_alloc_requests(struct uvc_video *video)
                 * max_t(unsigned int, video->ep->maxburst, 1)
                 * (video->ep->mult);
 
-       video->ureq = kcalloc(video->uvc_num_requests, sizeof(struct uvc_request), GFP_KERNEL);
-       if (video->ureq == NULL)
-               return -ENOMEM;
+       for (i = 0; i < video->uvc_num_requests; i++) {
+               ureq = kzalloc(sizeof(struct uvc_request), GFP_KERNEL);
+               if (ureq == NULL)
+                       goto error;
+
+               INIT_LIST_HEAD(&ureq->list);
+
+               list_add_tail(&ureq->list, &video->ureqs);
 
-       for (i = 0; i < video->uvc_num_requests; ++i) {
-               video->ureq[i].req_buffer = kmalloc(req_size, GFP_KERNEL);
-               if (video->ureq[i].req_buffer == NULL)
+               ureq->req_buffer = kmalloc(req_size, GFP_KERNEL);
+               if (ureq->req_buffer == NULL)
                        goto error;
 
-               video->ureq[i].req = usb_ep_alloc_request(video->ep, GFP_KERNEL);
-               if (video->ureq[i].req == NULL)
+               ureq->req = usb_ep_alloc_request(video->ep, GFP_KERNEL);
+               if (ureq->req == NULL)
                        goto error;
 
-               video->ureq[i].req->buf = video->ureq[i].req_buffer;
-               video->ureq[i].req->length = 0;
-               video->ureq[i].req->complete = uvc_video_complete;
-               video->ureq[i].req->context = &video->ureq[i];
-               video->ureq[i].video = video;
-               video->ureq[i].last_buf = NULL;
+               ureq->req->buf = ureq->req_buffer;
+               ureq->req->length = 0;
+               ureq->req->complete = uvc_video_complete;
+               ureq->req->context = ureq;
+               ureq->video = video;
+               ureq->last_buf = NULL;
 
-               list_add_tail(&video->ureq[i].req->list, &video->req_free);
+               list_add_tail(&ureq->req->list, &video->req_free);
                /* req_size/PAGE_SIZE + 1 for overruns and + 1 for header */
-               sg_alloc_table(&video->ureq[i].sgt,
+               sg_alloc_table(&ureq->sgt,
                               DIV_ROUND_UP(req_size - UVCG_REQUEST_HEADER_LEN,
                                            PAGE_SIZE) + 2, GFP_KERNEL);
        }
@@ -489,8 +497,8 @@ static void uvcg_video_pump(struct work_struct *work)
  */
 int uvcg_video_enable(struct uvc_video *video, int enable)
 {
-       unsigned int i;
        int ret;
+       struct uvc_request *ureq;
 
        if (video->ep == NULL) {
                uvcg_info(&video->uvc->func,
@@ -502,9 +510,10 @@ int uvcg_video_enable(struct uvc_video *video, int enable)
                cancel_work_sync(&video->pump);
                uvcg_queue_cancel(&video->queue, 0);
 
-               for (i = 0; i < video->uvc_num_requests; ++i)
-                       if (video->ureq && video->ureq[i].req)
-                               usb_ep_dequeue(video->ep, video->ureq[i].req);
+               list_for_each_entry(ureq, &video->ureqs, list) {
+                       if (ureq->req)
+                               usb_ep_dequeue(video->ep, ureq->req);
+               }
 
                uvc_video_free_requests(video);
                uvcg_queue_enable(&video->queue, 0);
@@ -536,6 +545,7 @@ int uvcg_video_enable(struct uvc_video *video, int enable)
  */
 int uvcg_video_init(struct uvc_video *video, struct uvc_device *uvc)
 {
+       INIT_LIST_HEAD(&video->ureqs);
        INIT_LIST_HEAD(&video->req_free);
        spin_lock_init(&video->req_lock);
        INIT_WORK(&video->pump, uvcg_video_pump);