From patchwork Tue Jun 23 19:08:31 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Elder X-Patchwork-Id: 4191 Return-Path: Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647]) by lancelot.ideasonboard.com (Postfix) with ESMTPS id 31BAB609A5 for ; Tue, 23 Jun 2020 21:09:43 +0200 (CEST) Authentication-Results: lancelot.ideasonboard.com; dkim=pass (1024-bit key; unprotected) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="oLYKeXvp"; dkim-atps=neutral Received: from jade.rasen.tech (unknown [IPv6:2400:4051:61:600:8147:f2a2:a8c6:9087]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 325F32A9; Tue, 23 Jun 2020 21:09:40 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1592939382; bh=QmBzW44/c3Lij4lDlWVU4mFM2PpO79VTOgCFGg0oEWI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oLYKeXvpSI17CT6tLHdxmE8+VrJcqyJyqYXOkBIm4D6nEFRfWDDlIhHzmDYsoNpxR LwTrrclvdSgw7Cvm9B+5MeXS2MQzO9ISdLuwu3lmBEAq43f4mrF54RAXBQLJ9wX0uY UzwjIPTxCGDGFwzO4qZLbjuH826umDd4QqjoTZAQ= From: Paul Elder To: libcamera-devel@lists.libcamera.org Date: Wed, 24 Jun 2020 04:08:31 +0900 Message-Id: <20200623190836.53446-18-paul.elder@ideasonboard.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200623190836.53446-1-paul.elder@ideasonboard.com> References: <20200623190836.53446-1-paul.elder@ideasonboard.com> MIME-Version: 1.0 Subject: [libcamera-devel] [PATCH v3 17/22] v4l2: v4l2_camera: Clear pending requests on freeBuffers and streamOff X-BeenThere: libcamera-devel@lists.libcamera.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 23 Jun 2020 19:09:43 -0000 V4L2 allows buffer queueing before streamon while libcamera does not. The compatibility layer thus saves these buffers in a pending queue until streamon, and then automatically queues them. However, this pending queue is not cleared when the buffers are freed, so the following sequence of actions will cause a use-after-free: 1. queue buffers 2. free buffers - buffers from 1. stay in pending queue but have been freed 3. queue buffers 4. streamon - buffers from 1. are enqueued, then the buffers from 3. are enqueued. Use-after-free segfault when libcamera tries to handle the enqueued buffers from 1. Fix this by clearing the pending request queue upon buffers being freed. Also clear the pending request queue on streamOff, for correctness. Signed-off-by: Paul Elder Reviewed-by: Jacopo Mondi Reviewed-by: Laurent Pinchart --- Changes in v3: - reorder clearing the pending request queue, to before freeing buffers, and to after checking isRunning Changes in v2: - also clear pending request queue on streamOff - clarify the issue in changelog --- src/v4l2/v4l2_camera.cpp | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/src/v4l2/v4l2_camera.cpp b/src/v4l2/v4l2_camera.cpp index bdf0036..ee6f907 100644 --- a/src/v4l2/v4l2_camera.cpp +++ b/src/v4l2/v4l2_camera.cpp @@ -149,6 +149,7 @@ void V4L2Camera::freeBuffers() { Stream *stream = *camera_->streams().begin(); + pendingRequests_.clear(); bufferAllocator_->free(stream); } @@ -189,10 +190,11 @@ int V4L2Camera::streamOn() int V4L2Camera::streamOff() { - /* \todo Restore buffers to reqbufs state? */ if (!isRunning_) return 0; + pendingRequests_.clear(); + int ret = camera_->stop(); if (ret < 0) return ret == -EACCES ? -EBUSY : ret;