diff mbox series

[v3,2/3] usb: gadget: uvc: Allocate uvc_requests one at a time

Message ID 20231005180814.3278050-2-arakesh@google.com (mailing list archive)
State Superseded
Headers show
Series [v3,1/3] usb: gadget: uvc: prevent use of disabled endpoint | expand

Commit Message

Avichal Rakesh Oct. 5, 2023, 6:08 p.m. UTC 
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
Suggested-by: Michael Grzeschik <mgr@pengutronix.de>
Signed-off-by: Avichal Rakesh <arakesh@google.com>
---
v1 -> v2: Rebased to ToT
V2 -> V3: Fix email threading goof-up

 drivers/usb/gadget/function/uvc.h       |  3 +-
 drivers/usb/gadget/function/uvc_video.c | 90 ++++++++++++++-----------
 2 files changed, 51 insertions(+), 42 deletions(-)

--
2.42.0.609.gbb76f46606-goog

Comments

Michael Grzeschik Oct. 6, 2023, 10:11 p.m. UTC | #1 
On Thu, Oct 05, 2023 at 11:08:13AM -0700, 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@google.com
>Suggested-by: Michael Grzeschik <mgr@pengutronix.de>

Please use my full address here. m.grzeschik@pengutronix.de

>Signed-off-by: Avichal Rakesh <arakesh@google.com>
>---
>v1 -> v2: Rebased to ToT
>V2 -> V3: Fix email threading goof-up
>
> drivers/usb/gadget/function/uvc.h       |  3 +-
> drivers/usb/gadget/function/uvc_video.c | 90 ++++++++++++++-----------
> 2 files changed, 51 insertions(+), 42 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 97d875c27dcf..3c4d286d81c0 100644
>--- a/drivers/usb/gadget/function/uvc_video.c
>+++ b/drivers/usb/gadget/function/uvc_video.c
>@@ -227,6 +227,23 @@ 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;
>@@ -299,27 +316,13 @@ 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);
>-
>-			if (video->ureq[i].req) {
>-				usb_ep_free_request(video->ep, video->ureq[i].req);
>-				video->ureq[i].req = NULL;
>-			}
>+	struct uvc_request *ureq, *temp;
>
>-			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);
> 	}

Please drop the extra braces.

>
>+	INIT_LIST_HEAD(&video->ureqs);
> 	INIT_LIST_HEAD(&video->req_free);
> 	video->req_size = 0;
> 	return 0;
>@@ -328,6 +331,7 @@ 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;
>@@ -338,29 +342,31 @@ 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) {
>-		video->ureq[i].req_buffer = kmalloc(req_size, GFP_KERNEL);
>-		if (video->ureq[i].req_buffer == NULL)
>+	INIT_LIST_HEAD(&video->ureqs);
>+	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);
>+	}
>
>-		video->ureq[i].req = usb_ep_alloc_request(video->ep, GFP_KERNEL);
>-		if (video->ureq[i].req == NULL)
>+	list_for_each_entry(ureq, &video->ureqs, list) {
>+		ureq->req_buffer = kmalloc(req_size, GFP_KERNEL);
>+		if (ureq->req_buffer == NULL)
> 			goto error;
>-

Instead of looping twice. Wouldn't it be possible to fill the
just created ureq from the for loop here directly.

>-		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;
>-
>-		list_add_tail(&video->ureq[i].req->list, &video->req_free);
>+		ureq->req = usb_ep_alloc_request(video->ep, GFP_KERNEL);
>+		if (ureq->req == NULL)
>+			goto error;
>+		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;

Add an extra spare line just like in the code before.

>+		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);
> 	}
>@@ -504,7 +510,7 @@ static void uvcg_video_pump(struct work_struct *work)
> int uvcg_video_enable(struct uvc_video *video, int enable)
> {
> 	struct uvc_device *uvc = video->uvc;
>-	unsigned int i;
>+	struct uvc_request *ureq;
> 	int ret;
>
> 	if (video->ep == NULL) {
>@@ -519,9 +525,10 @@ 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);
>@@ -555,6 +562,7 @@ 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);
>--
>2.42.0.609.gbb76f46606-goog
>
diff mbox series

Patch

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 97d875c27dcf..3c4d286d81c0 100644
--- a/drivers/usb/gadget/function/uvc_video.c
+++ b/drivers/usb/gadget/function/uvc_video.c
@@ -227,6 +227,23 @@  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;
@@ -299,27 +316,13 @@  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);
-
-			if (video->ureq[i].req) {
-				usb_ep_free_request(video->ep, video->ureq[i].req);
-				video->ureq[i].req = NULL;
-			}
+	struct uvc_request *ureq, *temp;

-			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;
@@ -328,6 +331,7 @@  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;
@@ -338,29 +342,31 @@  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) {
-		video->ureq[i].req_buffer = kmalloc(req_size, GFP_KERNEL);
-		if (video->ureq[i].req_buffer == NULL)
+	INIT_LIST_HEAD(&video->ureqs);
+	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);
+	}

-		video->ureq[i].req = usb_ep_alloc_request(video->ep, GFP_KERNEL);
-		if (video->ureq[i].req == NULL)
+	list_for_each_entry(ureq, &video->ureqs, list) {
+		ureq->req_buffer = kmalloc(req_size, GFP_KERNEL);
+		if (ureq->req_buffer == 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;
-
-		list_add_tail(&video->ureq[i].req->list, &video->req_free);
+		ureq->req = usb_ep_alloc_request(video->ep, GFP_KERNEL);
+		if (ureq->req == NULL)
+			goto error;
+		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(&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);
 	}
@@ -504,7 +510,7 @@  static void uvcg_video_pump(struct work_struct *work)
 int uvcg_video_enable(struct uvc_video *video, int enable)
 {
 	struct uvc_device *uvc = video->uvc;
-	unsigned int i;
+	struct uvc_request *ureq;
 	int ret;

 	if (video->ep == NULL) {
@@ -519,9 +525,10 @@  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);
@@ -555,6 +562,7 @@  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);