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Wed, 14 Dec 2022 08:32:21 -0800 (PST) Received: from alco.roam.corp.google.com ([100.104.168.209]) by smtp.gmail.com with ESMTPSA id ee48-20020a056402293000b004615f7495e0sm6395908edb.8.2022.12.14.08.32.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Dec 2022 08:32:20 -0800 (PST) From: Ricardo Ribalda Date: Wed, 14 Dec 2022 17:31:55 +0100 Subject: [PATCH v4] media: uvcvideo: Fix race condition with usb_kill_urb MIME-Version: 1.0 Message-Id: <20221212-uvc-race-v4-0-38d7075b03f5@chromium.org> To: Laurent Pinchart , Sergey Senozhatsky , Mauro Carvalho Chehab , Max Staudt Cc: linux-media@vger.kernel.org, stable@vger.kernel.org, Yunke Cao , Ricardo Ribalda , linux-kernel@vger.kernel.org X-Mailer: b4 0.11.0-dev-696ae X-Developer-Signature: v=1; a=openpgp-sha256; l=4414; i=ribalda@chromium.org; h=from:subject:message-id; bh=ogVdjybS9LEoywx0YwN/okaYfuH/y03AYQsWkydp3kQ=; b=owEBbQKS/ZANAwAKAdE30T7POsSIAcsmYgBjmfqNKqeDuIPruv3HRUGHzLrKhw0xXerfWXVR/oWJ Mh7m06eJAjMEAAEKAB0WIQREDzjr+/4oCDLSsx7RN9E+zzrEiAUCY5n6jQAKCRDRN9E+zzrEiGEBD/ 9paXuRWZxtIqzclORW4HCZGYi73FtH4rtSGo1FNlEq1R7vGpC1gQ796/GNRy0vTNoPO+QxaG6poI5J 8vAFLwLc3YCxAUXzcN/QuRqSznplWWU+TiGxWm/I2x+dlNbE0tk30rBktBkJ0rYvQev/gODgWCgghN JKnkI1XV3lxO9nCa/7WllWLHsNpjcGE0reWbaPRdpmwgQxUZyQsn0v1UjsGkI2EPfhhCBA9pLym2ie qJguxwajBM0LmK/ds6p5rVXdEmdz1BoOTa91s5QN89Qfu2n9gPljroekcxObhSEAR7A+TH4JCenRYJ zfstu4W4xhtU5LdCrdBumpkkOmxjw4mDZR4yYtH/asavDzAMEM98ceXIkSRT4ipCkbcQCeDfcD3339 e7BLYFB+fh7dO0R2dEZdw/i0vmr0gxk79TPbMbp/21RZutJPl/Ht2JMQfGOLfv/tojT7MT35xsEjqi ZTlGsBuRhEjLFLnjSEmAKs+AITV2Js6CV0xeCPwkwVkyyS/D4qhsv3NNxGuKjqvutOAcTKVaKNx7OD M75UhkjEUu9w2EF9WyCuIrjRO3YLkRQUrDrN9vqCGLuElX71HVPqqCTn9zxpYlYwQ2RnzYpt+fQe7k 4LxOvbbN2nLIE8NqmuMp9hiq5+moqyLr+SNq2O3Nlg0YoGQiXc424GQnJdlA== X-Developer-Key: i=ribalda@chromium.org; a=openpgp; fpr=9EC3BB66E2FC129A6F90B39556A0D81F9F782DA9 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1752208104024059594?= X-GMAIL-MSGID: =?utf-8?q?1752208104024059594?= usb_kill_urb warranties that all the handlers are finished when it returns, but does not protect against threads that might be handling asynchronously the urb. For UVC, the function uvc_ctrl_status_event_async() takes care of control changes asynchronously. If the code is executed in the following order: CPU 0 CPU 1 ===== ===== uvc_status_complete() uvc_status_stop() uvc_ctrl_status_event_work() uvc_status_start() -> FAIL Then uvc_status_start will keep failing and this error will be shown: <4>[ 5.540139] URB 0000000000000000 submitted while active drivers/usb/core/urb.c:378 usb_submit_urb+0x4c3/0x528 Let's improve the current situation, by not re-submiting the urb if we are stopping the status event. Also process the queued work (if any) during stop. CPU 0 CPU 1 ===== ===== uvc_status_complete() uvc_status_stop() uvc_status_start() uvc_ctrl_status_event_work() -> FAIL Hopefully, with the usb layer protection this should be enough to cover all the cases. Cc: stable@vger.kernel.org Fixes: e5225c820c05 ("media: uvcvideo: Send a control event when a Control Change interrupt arrives") Reviewed-by: Yunke Cao Signed-off-by: Ricardo Ribalda --- uvc: Fix race condition on uvc Make sure that all the async work is finished when we stop the status urb. To: Yunke Cao To: Sergey Senozhatsky To: Max Staudt To: Laurent Pinchart To: Mauro Carvalho Chehab Cc: linux-media@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- Changes in v4: - Replace bool with atomic_t to avoid compiler reordering - First complete the async work and then kill the urb to avoid race (Thanks Laurent!) - Link to v3: https://lore.kernel.org/r/20221212-uvc-race-v3-0-954efc752c9a@chromium.org Changes in v3: - Remove the patch for dev->status, makes more sense in another series, and makes the zero day less nervous. - Update reviewed-by (thanks Yunke!). - Link to v2: https://lore.kernel.org/r/20221212-uvc-race-v2-0-54496cc3b8ab@chromium.org Changes in v2: - Add a patch for not kalloc dev->status - Redo the logic mechanism, so it also works with suspend (Thanks Yunke!) - Link to v1: https://lore.kernel.org/r/20221212-uvc-race-v1-0-c52e1783c31d@chromium.org --- drivers/media/usb/uvc/uvc_ctrl.c | 3 +++ drivers/media/usb/uvc/uvc_status.c | 6 ++++++ drivers/media/usb/uvc/uvcvideo.h | 1 + 3 files changed, 10 insertions(+) --- base-commit: 0ec5a38bf8499f403f81cb81a0e3a60887d1993c change-id: 20221212-uvc-race-09276ea68bf8 Best regards, diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c index c95a2229f4fa..1be6897a7d6d 100644 --- a/drivers/media/usb/uvc/uvc_ctrl.c +++ b/drivers/media/usb/uvc/uvc_ctrl.c @@ -1442,6 +1442,9 @@ static void uvc_ctrl_status_event_work(struct work_struct *work) uvc_ctrl_status_event(w->chain, w->ctrl, w->data); + if (atomic_read(&dev->flush_status)) + return; + /* Resubmit the URB. */ w->urb->interval = dev->int_ep->desc.bInterval; ret = usb_submit_urb(w->urb, GFP_KERNEL); diff --git a/drivers/media/usb/uvc/uvc_status.c b/drivers/media/usb/uvc/uvc_status.c index 7518ffce22ed..4a95850cdc1b 100644 --- a/drivers/media/usb/uvc/uvc_status.c +++ b/drivers/media/usb/uvc/uvc_status.c @@ -304,10 +304,16 @@ int uvc_status_start(struct uvc_device *dev, gfp_t flags) if (dev->int_urb == NULL) return 0; + atomic_set(&dev->flush_status, 0); return usb_submit_urb(dev->int_urb, flags); } void uvc_status_stop(struct uvc_device *dev) { + struct uvc_ctrl_work *w = &dev->async_ctrl; + + atomic_set(&dev->flush_status, 1); + if (cancel_work_sync(&w->work)) + uvc_ctrl_status_event(w->chain, w->ctrl, w->data); usb_kill_urb(dev->int_urb); } diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h index df93db259312..1274691f157f 100644 --- a/drivers/media/usb/uvc/uvcvideo.h +++ b/drivers/media/usb/uvc/uvcvideo.h @@ -560,6 +560,7 @@ struct uvc_device { struct usb_host_endpoint *int_ep; struct urb *int_urb; u8 *status; + atomic_t flush_status; struct input_dev *input; char input_phys[64];