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@xxxxxxxxxx >> Suggested-by: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx> >> Reviewed-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 >> >> 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 >> >> >
