From nobody Tue Sep 16 13:47:26 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 611B5C4708E for ; Mon, 2 Jan 2023 12:54:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235986AbjABMyV (ORCPT ); Mon, 2 Jan 2023 07:54:21 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56070 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235976AbjABMyK (ORCPT ); Mon, 2 Jan 2023 07:54:10 -0500 Received: from mail-ej1-x62e.google.com (mail-ej1-x62e.google.com [IPv6:2a00:1450:4864:20::62e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C5492392 for ; Mon, 2 Jan 2023 04:54:08 -0800 (PST) Received: by mail-ej1-x62e.google.com with SMTP id t17so66369712eju.1 for ; Mon, 02 Jan 2023 04:54:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=cc:to:message-id:content-transfer-encoding:mime-version:subject :date:from:from:to:cc:subject:date:message-id:reply-to; bh=4mSpRdBbR8hRsjiFVakEqY6OCTQghFDsF57WE7uaZ24=; b=ftNK/aNTJUYoLnNPnZtpYA0c2auYvuuZKBly8Ot7SG7yW80AnySckkTePJ4xHSKbVs qGWNQ+TBR+xT8+ytjem9zJrRHsBevryPUeqG17zBdheg1DsgTDoYTELa/DS0kb6V6qhR 71JZNOJMfUTcRck6vbmmnqo392zr6FgeXCnOg= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:message-id:content-transfer-encoding:mime-version:subject :date:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=4mSpRdBbR8hRsjiFVakEqY6OCTQghFDsF57WE7uaZ24=; b=8IToRoqD0wteOy3t04sLzx8qvuLek07U7cHbnJLftmdroXb6/gmb2RrYT4YJi0Rvet vPqsUOSs+zONZbi0iyjHOHJVgVbmlZ+9zuneEs9VcZo7YCY90TNKZhskku9EmiC8/J4y 2vukLVnpznnHSsuDUmzX4OcmIVIb3m9R3/SRFEY8jnDn0+0MNq/Mxd7b5mVgeeHpY7EF M7V51e/md+Ihi7PZbc9aqvsY09P/xw8MXPt56hixBCWA80fzXF39Fy5togW+NGOqMljs Glu4epNuqmDcaIA3Z3cCuzbeDVfRLXkK1b3DGCm2rAUg4Hpa/Bi63g1sCxZ2uIHx7Gur kGAw== X-Gm-Message-State: AFqh2kpeex2P9aAPk6r/JZzGbQAO70bcUmXxIPn5dHgz1VnHAYUzMNh3 jWuF1v1wmqslQcA7p0uNCmnAzg== X-Google-Smtp-Source: AMrXdXtKnal3J9pm26arZI9MbJIEvGdKx3JHk0FBnpKk8LqbC79A6lGLoOjRyMQqd+u8Jb8OqFug2w== X-Received: by 2002:a17:906:9f07:b0:7c1:6f0a:a2cf with SMTP id fy7-20020a1709069f0700b007c16f0aa2cfmr35989436ejc.32.1672664047325; Mon, 02 Jan 2023 04:54:07 -0800 (PST) Received: from alco.roam.corp.google.com ([2620:0:1059:10:6ef6:ea10:76ec:977f]) by smtp.gmail.com with ESMTPSA id j15-20020a170906094f00b007add28659b0sm13205598ejd.140.2023.01.02.04.54.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Jan 2023 04:54:06 -0800 (PST) From: Ricardo Ribalda Date: Mon, 02 Jan 2023 13:53:38 +0100 Subject: [PATCH v5] media: uvcvideo: Fix race condition with usb_kill_urb MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20221212-uvc-race-v5-0-3db3933d1608@chromium.org> To: Sergey Senozhatsky , Mauro Carvalho Chehab , Laurent Pinchart , Max Staudt Cc: linux-media@vger.kernel.org, stable@vger.kernel.org, linux-kernel@vger.kernel.org, Yunke Cao , Ricardo Ribalda X-Mailer: b4 0.11.0-dev-696ae X-Developer-Signature: v=1; a=openpgp-sha256; l=5506; i=ribalda@chromium.org; h=from:subject:message-id; bh=+NHyWPvCyiTeSkvSubZaZ/Q7vNEi0zyCacfqmuUFlec=; b=owEBbQKS/ZANAwAKAdE30T7POsSIAcsmYgBjstPpb14iWK6RcBI4U/PFcjqha1VTQAciMfENYSVQ E6oV2xWJAjMEAAEKAB0WIQREDzjr+/4oCDLSsx7RN9E+zzrEiAUCY7LT6QAKCRDRN9E+zzrEiJciD/ 0QhKqGkYR0UyIX7FhHkAGoH2TSg5zA4GQlTlCH0inYvovIfE9a5nql/WSl+nfDPU0UOiAJyZQhx9EI Gwze+7gey1+WYXHo8oexhS1zHupNXWoaGwaEH1Om/HAU6/PGYOon81TxK2bXf+rM7JP2/J8tn++S07 0bTPCCHDx2cJPvIwgkUqXM1qzPZdwXnEshv9A/jgK+1A9MOY92TbF5D2mR7cakcOLM5XAonXViFxh2 Rxehg952173WD5jLzxamdCB4WOPXIp7Pa/P2PTb0gQjUg6VYbc+Oi0SX11PE4sGC1TRl212XzyeaxL uUlxbbdWnsZpa/qb87rDF0isbHmFuySVBTn51CmAxiJ2dNw/sqhqkiec1O0FOnP2NpIWkytOkttlSu Vm8OpvXvAJZvAm58PcddIrO3qURhQw9HLFl18OzTOxu+KsQicyi3WvVuQNzZLQYcRrEpAnszDliUL0 +KE09fP90LTCQ5XkYTSgTONgDX7VT6rLpnQVfOMxG4QOLq3ITax+hChTLBcUDXhHgfQXFV7giThyO9 HQo3G8IPLQ0jMlhmLioRuFDRsynLnYoluMJ90rhHZMkGhyX/7A49d/qCEp1dZk5qavxu5CPfdo7xTy pLt7dpATJQ9o2TY3vjqEqDbvzW8IVLjC0pG8HCjaI6MWGOlbsFJkjQPzzihg== X-Developer-Key: i=ribalda@chromium.org; a=openpgp; fpr=9EC3BB66E2FC129A6F90B39556A0D81F9F782DA9 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 =3D=3D=3D=3D=3D =3D=3D=3D=3D=3D 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 =3D=3D=3D=3D=3D =3D=3D=3D=3D=3D 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 v5: - atomic_t do not impose barriers, use smp_mb() instead. (Thanks Laurent) - Add an extra cancel_work_sync(). - Link to v4: https://lore.kernel.org/r/20221212-uvc-race-v4-0-38d7075b03f5= @chromium.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 | 36 ++++++++++++++++++++++++++++++++++= ++ drivers/media/usb/uvc/uvcvideo.h | 1 + 3 files changed, 40 insertions(+) diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_c= trl.c index c95a2229f4fa..5160facc8e20 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_st= ruct *work) =20 uvc_ctrl_status_event(w->chain, w->ctrl, w->data); =20 + if (dev->flush_status) + return; + /* Resubmit the URB. */ w->urb->interval =3D dev->int_ep->desc.bInterval; ret =3D 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..5911e63776e1 100644 --- a/drivers/media/usb/uvc/uvc_status.c +++ b/drivers/media/usb/uvc/uvc_status.c @@ -6,6 +6,7 @@ * Laurent Pinchart (laurent.pinchart@ideasonboard.com) */ =20 +#include #include #include #include @@ -309,5 +310,40 @@ int uvc_status_start(struct uvc_device *dev, gfp_t fla= gs) =20 void uvc_status_stop(struct uvc_device *dev) { + struct uvc_ctrl_work *w =3D &dev->async_ctrl; + + /* From this point, the status urb is not re-queued */ + dev->flush_status =3D 1; + /* + * Make sure that the other CPUs are aware of the new value of + * flush_status. + */ + smp_mb(); + + /* If there is any status event on the queue, process it. */ + if (cancel_work_sync(&w->work)) + uvc_ctrl_status_event(w->chain, w->ctrl, w->data); + + /* Kill the urb. */ usb_kill_urb(dev->int_urb); + + /* + * If an status event was queued between cancel_work_sync() and + * usb_kill_urb(), process it. + */ + if (cancel_work_sync(&w->work)) + uvc_ctrl_status_event(w->chain, w->ctrl, w->data); + + /* + * From this point, there are no events on the queue and the status urb + * is dead, this is, no events will be queued until uvc_status_start() + * is called. + */ + dev->flush_status =3D 0; + /* + * Write to memory the value of flush_status before uvc_status_start() + * is called again, + */ + smp_mb(); + } diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvi= deo.h index df93db259312..6a9b72d6789e 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; + bool flush_status; struct input_dev *input; char input_phys[64]; =20 --- base-commit: 0ec5a38bf8499f403f81cb81a0e3a60887d1993c change-id: 20221212-uvc-race-09276ea68bf8 Best regards, --=20 Ricardo Ribalda