Re: [PATCH v10 2/4] usb: gadget: uvc: Allocate uvc_requests one at a time
From: Dan Scally
Date: Wed Nov 01 2023 - 07:06:23 EST
Morning Avichal
On 30/10/2023 20:22, Avichal Rakesh wrote:
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@xxxxxxxxxx
Suggested-by: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx>
Reviewed-by: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx>
Tested-by: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx>
Signed-off-by: Avichal Rakesh <arakesh@xxxxxxxxxx>
Thanks for the update; this seems ok now:
Reviewed-by: Daniel Scally <dan.scally@xxxxxxxxxxxxxxxx>
---
v1 -> v2 : Rebased to ToT
v2 -> v3 : Fix email threading goof-up
v3 -> v4 : Address review comments & re-rebase to ToT
v4 -> v5 : Address more review comments. Add Reviewed-by & Tested-by.
v5 -> v6 : No change
v6 -> v7 : No change
v7 -> v8 : No change. Getting back in review queue
v8 -> v9 : Address review comments.
v9 -> v10: Address review comments; remove BUG_ON(&video->reqs);
Rebase to ToT (usb-next)
drivers/usb/gadget/function/uvc.h | 3 +-
drivers/usb/gadget/function/uvc_video.c | 88 ++++++++++++++-----------
2 files changed, 51 insertions(+), 40 deletions(-)
diff --git a/drivers/usb/gadget/function/uvc.h b/drivers/usb/gadget/function/uvc.h
index 989bc6b4e93d..993694da0bbc 100644
--- 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 c334802ac0a4..1619f9664748 100644
--- 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);
--
2.42.0.820.g83a721a137-goog