{"id":18311,"url":"https://patchwork.libcamera.org/api/patches/18311/?format=json","web_url":"https://patchwork.libcamera.org/patch/18311/","project":{"id":1,"url":"https://patchwork.libcamera.org/api/projects/1/?format=json","name":"libcamera","link_name":"libcamera","list_id":"libcamera_core","list_email":"libcamera-devel@lists.libcamera.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20230227203947.3964157-1-kieran.bingham@ideasonboard.com>","date":"2023-02-27T20:39:47","name":"[libcamera-devel] v4l2: v4l2_camera_proxy: Detect ioctl sign-extensions","commit_ref":null,"pull_url":null,"state":"superseded","archived":false,"hash":"6ae6f5ba0594c342044f39eae69d1eb88e75d1fb","submitter":{"id":4,"url":"https://patchwork.libcamera.org/api/people/4/?format=json","name":"Kieran Bingham","email":"kieran.bingham@ideasonboard.com"},"delegate":null,"mbox":"https://patchwork.libcamera.org/patch/18311/mbox/","series":[{"id":3772,"url":"https://patchwork.libcamera.org/api/series/3772/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=3772","date":"2023-02-27T20:39:47","name":"[libcamera-devel] v4l2: v4l2_camera_proxy: Detect ioctl sign-extensions","version":1,"mbox":"https://patchwork.libcamera.org/series/3772/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/18311/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/18311/checks/","tags":{},"headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id DA46CBE08A\n\tfor ;\n\tMon, 27 Feb 2023 20:39:52 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 4C77662682;\n\tMon, 27 Feb 2023 21:39:52 +0100 (CET)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 7897C6265A\n\tfor ;\n\tMon, 27 Feb 2023 21:39:51 +0100 (CET)","from Monstersaurus.tail69b4.ts.net\n\t(cpc89244-aztw30-2-0-cust3082.18-1.cable.virginm.net [86.31.172.11])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id D7713B6C;\n\tMon, 27 Feb 2023 21:39:50 +0100 (CET)"],"DKIM-Signature":["v=1; a=rsa-sha256; c=relaxed/simple; d=libcamera.org;\n\ts=mail; t=1677530392;\n\tbh=+u8FEk7YJk4LFsAu76n1VZ5vxvx6FzJyjBfudTVNRbM=;\n\th=To:Date:Subject:List-Id:List-Unsubscribe:List-Archive:List-Post:\n\tList-Help:List-Subscribe:From:Reply-To:From;\n\tb=K4Pyn4X1u9yKpiUZTEDNKEAW+IhrNk1Tyn4PwHsB6ju/7ezXvOSgXy9cUAJLuoA4L\n\tIP/attLADgqlP7W7dHpp+sIiYcouBjuvX88WA3Hx66bcld1IM7YQbTN7LVipgAyY7w\n\tCyy09CrfNcQ8SidNaMWCi7RTc8w4ZxWfEcflW6UCZUEawvsDKsrI2wtZkpkltOM5aw\n\tnqfmuk8lFOnzLAA4fHUJBNkceuaY6fmvUCL7STOA5y2QAHoG3/1Q8MvdIA9zyGcham\n\tZWMxFt9HfL/o+nEN7/6XlfgBNuxDdP79cIT+vW2aA8sU1TEXET2mZTSiki09uDEM1l\n\tfDO2aObo1c/4Q==","v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1677530391;\n\tbh=+u8FEk7YJk4LFsAu76n1VZ5vxvx6FzJyjBfudTVNRbM=;\n\th=From:To:Cc:Subject:Date:From;\n\tb=aDhf1GFXhfNAN71Ia+G9jxiu20oTdg6PSZVowBdQy9dbEhuWflz64vocoooib4qJ7\n\tOkWTmeCBfQ8uc7DPHRy+eD8Lvfz8BrxtXM+bCtp5UCX5j3fbh/UA9Vll9OQmqY4/Bb\n\tNdqEBttCovp5SvtlXLqWTbNqKVhzMB85dWHxxHS8="],"Authentication-Results":"lancelot.ideasonboard.com; dkim=pass (1024-bit key; \n\tunprotected) header.d=ideasonboard.com\n\theader.i=@ideasonboard.com\n\theader.b=\"aDhf1GFX\"; dkim-atps=neutral","To":"libcamera devel ","Date":"Mon, 27 Feb 2023 20:39:47 +0000","Message-Id":"<20230227203947.3964157-1-kieran.bingham@ideasonboard.com>","X-Mailer":"git-send-email 2.34.1","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit","Subject":"[libcamera-devel] [PATCH] v4l2: v4l2_camera_proxy: Detect ioctl\n\tsign-extensions","X-BeenThere":"libcamera-devel@lists.libcamera.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","From":"Kieran Bingham via libcamera-devel\n\t","Reply-To":"Kieran Bingham ","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "},"content":"Handling ioctl's within applications is often wrapped with a helper such\nas xioctl. Unfortunately, there are many instances of xioctl which\nincorrectly handle the correct size of the ioctl request.\n\nThis leads to incorrect sign-extension of ioctl's which have bit-31 set,\nand can cause values to be passed into the libcamera's v4l2 adaptation\nlayer which no longer represent the true IOCTL code.\n\nWe can easily identify if an application has mistakenly sign-extended an\nioctl command request and mask out those bits.\n\nDo so and report the error loudly, but only once that the application\nshould be fixed.\n\nSigned-off-by: Kieran Bingham \n---\n\nThis is a pain. It's not 'libcamera's' fault. But we can do something\nabout it.\n\nSee\n - https://github.com/kbingham/libcamera/issues/69\nand\n - https://github.com/Motion-Project/motion/discussions/1636\n\n\n\n src/v4l2/v4l2_camera_proxy.cpp | 18 ++++++++++++++++++\n 1 file changed, 18 insertions(+)","diff":"diff --git a/src/v4l2/v4l2_camera_proxy.cpp b/src/v4l2/v4l2_camera_proxy.cpp\nindex 55ff62cdb430..75c53aedf2fa 100644\n--- a/src/v4l2/v4l2_camera_proxy.cpp\n+++ b/src/v4l2/v4l2_camera_proxy.cpp\n@@ -782,6 +782,24 @@ int V4L2CameraProxy::ioctl(V4L2CameraFile *file, unsigned long request, void *ar\n {\n \tMutexLocker locker(proxyMutex_);\n \n+\t/*\n+\t * Applications may easily find themselves incorrectly sign-extending\n+\t * ioctls on 64-bit systems which can cause hard to diagnose failures\n+\t * with the v4l2-adatation layer. Identify this failure, and work\n+\t * around it - but report the issue as it should be fixed in the\n+\t * application.\n+\t */\n+\tif (request & 0xffffffff00000000) {\n+\t\tstatic bool warnOnce = true;\n+\n+\t\tif (warnOnce) {\n+\t\t\tLOG(V4L2Compat, Error) << \"ioctl sign extension detected.\";\n+\t\t\tLOG(V4L2Compat, Error) << \"Please fix your application.\";\n+\t\t\twarnOnce = false;\n+\t\t}\n+\t\trequest &= 0xffffffff;\n+\t}\n+\n \tif (!arg && (_IOC_DIR(request) & _IOC_WRITE)) {\n \t\terrno = EFAULT;\n \t\treturn -1;\n","prefixes":["libcamera-devel"]}