On 10/28/23 13:13, Dan Scally wrote: > Hi Avichal > > On 27/10/2023 21:19, 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: Daniel Scally <dan.scally@xxxxxxxxxxxxxxxx> > > > Sorry - I was unclear in my response to the first patch on v8. I meant my R-b to apply to the first patch only rather than to all of them. For this one I understand now the use of the conditional in uvc_video_free_request(), so that point is fine. I agree with Greg that the BUG_ON() shouldn't stand though. Ah, didn't realize BUG_ON is discouraged. Removed BUG_ON. It was supposed to be a defensive bit of code anyway, so removing the check entirely. If the state is inconsistent, we'd see other errors, so the BUG_ON wasn't providing value anyway. Also removed your Reviewed-by, my apologies. > >> Reviewed-by: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx> >> Tested-by: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx> >> Signed-off-by: Avichal Rakesh <arakesh@xxxxxxxxxx> >> --- >> 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. >> >> drivers/usb/gadget/function/uvc.h | 3 +- >> drivers/usb/gadget/function/uvc_video.c | 89 ++++++++++++++----------- >> 2 files changed, 52 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..f8f9209fee50 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; >> @@ -322,39 +325,45 @@ 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; >> >> BUG_ON(video->req_size); >> + BUG_ON(!list_empty(&video->ureqs)); >> >> req_size = video->ep->maxpacket >> * 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 +498,8 @@ 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 +511,10 @@ 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 +546,7 @@ 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
