From patchwork Tue Jul 18 15:29:17 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Milan Zamazal X-Patchwork-Id: 13317413 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 DF310EB64DA for ; Tue, 18 Jul 2023 15:33:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233790AbjGRPdP (ORCPT ); Tue, 18 Jul 2023 11:33:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60552 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232005AbjGRPc4 (ORCPT ); Tue, 18 Jul 2023 11:32:56 -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 F130FE52 for ; Tue, 18 Jul 2023 08:32:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1689694323; 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=Nze9cEhxidO799p4WuWgw+8RBtrm/EbtjYeDGWps2R4=; b=I2vMtcBrAZSeFh/ooBl95jQmbpxshLIpQRwzZCeDCWETKE/WJgA7VmhU03/QO3R9/s6iMW 0Hjtstl6vyYTOtS98/BJoDV93NRf/SGe0/qKx83Do+uTbrQF2NPj6eu/BFDK5maEuR+F4r FxIrN0HJZSXQ4NFGBMyPiw3oqU8+TPs= 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-262-PHzj08aHPEWzaEUacDIGdw-1; Tue, 18 Jul 2023 11:32:01 -0400 X-MC-Unique: PHzj08aHPEWzaEUacDIGdw-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 AB7DE8DC6F6; Tue, 18 Jul 2023 15:30:06 +0000 (UTC) Received: from localhost.localdomain (unknown [10.34.131.165]) by smtp.corp.redhat.com (Postfix) with ESMTP id A1E7640C206F; Tue, 18 Jul 2023 15:30:05 +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 v2] iio: core: Prevent invalid memory access when there is no parent Date: Tue, 18 Jul 2023 17:29:17 +0200 Message-Id: <20230718152917.435962-1-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: ... asm_exc_page_fault container_offline __iio_device_register krealloc iio_device_attach_buffer iio_simple_dummy_configure_buffer iio_triggered_buffer_setup_ext iio_dummy_probe iio_sw_device_create device_make_group configfs_mkdir 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") Signed-off-by: Milan Zamazal Reviewed-by: Andy Shevchenko --- 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);