From patchwork Wed Jul 19 08:32:08 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Milan Zamazal X-Patchwork-Id: 13318581 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 88F9BC001B0 for ; Wed, 19 Jul 2023 08:33:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229997AbjGSIdD (ORCPT ); Wed, 19 Jul 2023 04:33:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35844 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229461AbjGSIdC (ORCPT ); Wed, 19 Jul 2023 04:33:02 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AC824172E for ; Wed, 19 Jul 2023 01:32:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1689755538; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=hLVWiQaUIoFXyBvJ0khKrsLYliZnwHQCbXVd/dMmGbc=; b=bkhZSzfYOpW/M++A3O9J29CPbFMmfvo2M/VfF6A3MoRQf4Nbu6VjA4VHsvH5Ny55XplREz YjiR7XZhpq4Haw5cJojJG8JmRlgU3jmdo2x7QtRTzfSSUyXfURTp72r88Zzzn4/2N2WcHu e6VvteWCMDxzqHRa3oZyRgbFbkfCl6Q= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-558-FTUf81MPMS-KVpZxJl255w-1; Wed, 19 Jul 2023 04:32:15 -0400 X-MC-Unique: FTUf81MPMS-KVpZxJl255w-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id F14788F184F; Wed, 19 Jul 2023 08:32:14 +0000 (UTC) Received: from nuthatch.redhat.com (unknown [10.45.225.207]) by smtp.corp.redhat.com (Postfix) with ESMTP id BFBF140C2070; Wed, 19 Jul 2023 08:32:13 +0000 (UTC) From: Milan Zamazal To: linux-iio@vger.kernel.org Cc: Milan Zamazal , linux-kernel@vger.kernel.org, Jonathan Cameron , Lars-Peter Clausen , Andy Shevchenko , =?utf-8?q?Nuno_S=C3=A1?= Subject: [PATCH v3] iio: core: Prevent invalid memory access when there is no parent Date: Wed, 19 Jul 2023 10:32:08 +0200 Message-Id: <20230719083208.88149-1-mzamazal@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org Commit 813665564b3d ("iio: core: Convert to use firmware node handle instead of OF node") switched the kind of nodes to use for label retrieval in device registration. Probably an unwanted change in that commit was that if the device has no parent then NULL pointer is accessed. This is what happens in the stock IIO dummy driver when a new entry is created in configfs: # mkdir /sys/kernel/config/iio/devices/dummy/foo BUG: kernel NULL pointer dereference, address: ... ... Call Trace: __iio_device_register iio_dummy_probe Since there seems to be no reason to make a parent device of an IIO dummy device mandatory, let’s prevent the invalid memory access in __iio_device_register when the parent device is NULL. With this change, the IIO dummy driver works fine with configfs. Fixes: 813665564b3d ("iio: core: Convert to use firmware node handle instead of OF node") Reviewed-by: Andy Shevchenko Signed-off-by: Milan Zamazal --- Changes in v3: - The call trace in the commit message reduced to the minimum lines needed to explain the problem. Changes in v2: - Added a source comment about the dummy IIO device. - Adjusted the backtrace cited in the commit message a bit. - Replaced `... != NULL' condition with `...'. - Dropped the unnecessary `fwnode != NULL' check (the involved calls do the right thing when the argument is NULL). --- drivers/iio/industrialio-core.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c index c117f50d0cf3..adcba832e6fa 100644 --- a/drivers/iio/industrialio-core.c +++ b/drivers/iio/industrialio-core.c @@ -1888,7 +1888,7 @@ static const struct iio_buffer_setup_ops noop_ring_setup_ops; int __iio_device_register(struct iio_dev *indio_dev, struct module *this_mod) { struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev); - struct fwnode_handle *fwnode; + struct fwnode_handle *fwnode = NULL; int ret; if (!indio_dev->info) @@ -1899,7 +1899,8 @@ int __iio_device_register(struct iio_dev *indio_dev, struct module *this_mod) /* If the calling driver did not initialize firmware node, do it here */ if (dev_fwnode(&indio_dev->dev)) fwnode = dev_fwnode(&indio_dev->dev); - else + /* The default dummy IIO device has no parent */ + else if (indio_dev->dev.parent) fwnode = dev_fwnode(indio_dev->dev.parent); device_set_node(&indio_dev->dev, fwnode);