diff mbox series

[v4,2/3] usb: gadget: uvc: Allocate uvc_requests one at a time

Message ID 20231012002451.254737-2-arakesh@google.com
State Superseded
Headers show
Series None | expand

Commit Message

Avichal Rakesh Oct. 12, 2023, 12:24 a.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 <m.grzeschik@pengutronix.de>
Reviewed-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Signed-off-by: Avichal Rakesh <arakesh@google.com>
---
v1 -> v2: Rebased to ToT
v2 -> v3: Fix email threading goof-up
v3 -> v4: Address review comments & re-rebase to ToT

 drivers/usb/gadget/function/uvc.h       |  3 +-
 drivers/usb/gadget/function/uvc_video.c | 87 ++++++++++++++-----------
 2 files changed, 50 insertions(+), 40 deletions(-)

--
2.42.0.609.gbb76f46606-goog

Comments

Michael Grzeschik Oct. 18, 2023, 1:03 p.m. UTC | #1
A short second review.

On Wed, Oct 11, 2023 at 05:24:50PM -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 <m.grzeschik@pengutronix.de>
>Reviewed-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
>Signed-off-by: Avichal Rakesh <arakesh@google.com>
>---
>v1 -> v2: Rebased to ToT
>v2 -> v3: Fix email threading goof-up
>v3 -> v4: Address review comments & re-rebase to ToT
>
> drivers/usb/gadget/function/uvc.h       |  3 +-
> drivers/usb/gadget/function/uvc_video.c | 87 ++++++++++++++-----------
> 2 files changed, 50 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..b62b3de79153 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;
>+	struct uvc_request *ureq, *temp;
>
>-	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;
>-			}
>-
>-			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 +336,32 @@ 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;
>+	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;
Please add an empty line here.
>+		INIT_LIST_HEAD(&ureq->list);

Please add an empty line here.

>+		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)
You could also use if (!ureq->req_buffer)

> 			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 +496,8 @@ 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 +509,10 @@ 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 +544,7 @@ 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
>
>
Avichal Rakesh Oct. 18, 2023, 7:53 p.m. UTC | #2
On 10/18/23 06:03, Michael Grzeschik wrote:
> A short second review.

Thank you for the review. Sent out a v5 with the comments 
addressed!

> 
> On Wed, Oct 11, 2023 at 05:24:50PM -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 <m.grzeschik@pengutronix.de>
>> Reviewed-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
>> Signed-off-by: Avichal Rakesh <arakesh@google.com>
>> ---
>> v1 -> v2: Rebased to ToT
>> v2 -> v3: Fix email threading goof-up
>> v3 -> v4: Address review comments & re-rebase to ToT
>>
>> drivers/usb/gadget/function/uvc.h       |  3 +-
>> drivers/usb/gadget/function/uvc_video.c | 87 ++++++++++++++-----------
>> 2 files changed, 50 insertions(+), 40 deletions(-)
>> -        if (video->ureq[i].req_buffer == NULL)
>> +        ureq->req_buffer = kmalloc(req_size, GFP_KERNEL);
>> +        if (ureq->req_buffer == NULL)
> You could also use if (!ureq->req_buffer)

Keeping this as is because I prefer `== NULL` check for readability.
Didn't find any specific rules in the kernel codestyle, so sticking
with the more readable option (in my opinion).

> 
>>             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 +496,8 @@ 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 +509,10 @@ 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 +544,7 @@ 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 c334802ac0a4..b62b3de79153 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;
+	struct uvc_request *ureq, *temp;

-	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;
-			}
-
-			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 +336,32 @@  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;
+	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);

-	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 +496,8 @@  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 +509,10 @@  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 +544,7 @@  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);