From patchwork Wed Jun 24 14:52:51 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Elder X-Patchwork-Id: 8415 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 9BA82609B3 for ; Wed, 24 Jun 2020 16:53:56 +0200 (CEST) Authentication-Results: lancelot.ideasonboard.com; dkim=pass (1024-bit key; unprotected) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="Rky2R81w"; 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 7A16A2A8; Wed, 24 Jun 2020 16:53:54 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1593010436; bh=+JZqZReMXotnIPxlzWAao6FhXtvnDG+Qy2Bxax/Och4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Rky2R81wXN7tKS+zQtH67AZwSrg/u4t2GY7YJgwtnrzOuBR6ZitOwKNpJ5n97/BVU h/oB6n+k5oMKVw+mmqjHkiE0NVHLKZloP9L+FO7fIWoT1yzgjG5qBPZMtXemS2nnUA 9UDP6BHT1wm69tLmwExOuagIy7CBQNCB9NNiGxxM= From: Paul Elder To: libcamera-devel@lists.libcamera.org Date: Wed, 24 Jun 2020 23:52:51 +0900 Message-Id: <20200624145256.48266-18-paul.elder@ideasonboard.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200624145256.48266-1-paul.elder@ideasonboard.com> References: <20200624145256.48266-1-paul.elder@ideasonboard.com> MIME-Version: 1.0 Subject: [libcamera-devel] [PATCH v4 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: Wed, 24 Jun 2020 14:53:56 -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 --- No change in v4 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 | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/src/v4l2/v4l2_camera.cpp b/src/v4l2/v4l2_camera.cpp index f7df9b8..ffc1230 100644 --- a/src/v4l2/v4l2_camera.cpp +++ b/src/v4l2/v4l2_camera.cpp @@ -147,6 +147,8 @@ int V4L2Camera::allocBuffers(unsigned int count) void V4L2Camera::freeBuffers() { + pendingRequests_.clear(); + Stream *stream = *camera_->streams().begin(); bufferAllocator_->free(stream); } @@ -188,10 +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;