From patchwork Mon Sep 16 16:11:22 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 1162982 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=linux-gpio-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=kernel.org Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="NPHXM9df"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 46XB7n0DPJz9sPw for ; Tue, 17 Sep 2019 02:11:33 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726442AbfIPQLc (ORCPT ); Mon, 16 Sep 2019 12:11:32 -0400 Received: from mail.kernel.org ([198.145.29.99]:50910 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726282AbfIPQLb (ORCPT ); Mon, 16 Sep 2019 12:11:31 -0400 Received: from localhost.localdomain (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2A05220678; Mon, 16 Sep 2019 16:11:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568650291; bh=U7t59ayezt+kXdtbAjHQuUkbsPCfO+CUYQiNwJ/mbuY=; h=From:To:Cc:Subject:Date:From; b=NPHXM9dfNy6r/dDzw/+cc5xnFABgLsRKh41hg/jq6AUtCrX1+jS6rGKJJx8jSWQbY 6BPZEvKJTcSk0DdkFu0g4vBMW61QAOJrPQoXjj3YG0rn0+qVsrlulvYFClVgyJ2qTm jUiUbrdMC+CzU1jANhPRaPnzdxvIze/lAfWd9nHE= From: Will Deacon To: linux-gpio@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Will Deacon , Linus Walleij Subject: [PATCH] pinctrl: devicetree: Avoid taking direct reference to device name string Date: Mon, 16 Sep 2019 17:11:22 +0100 Message-Id: <20190916161122.12166-1-will@kernel.org> X-Mailer: git-send-email 2.11.0 Sender: linux-gpio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org When populating the pinctrl mapping table entries for a device, the 'dev_name' field for each entry is initialised to point directly at the string returned by 'dev_name()' for the device and subsequently used by 'create_pinctrl()' when looking up the mappings for the device being probed. This is unreliable in the presence of calls to 'dev_set_name()', which may reallocate the device name string leaving the pinctrl mappings with a dangling reference. This then leads to a use-after-free every time the name is dereferenced by a device probe: | BUG: KASAN: invalid-access in strcmp+0x20/0x64 | Read of size 1 at addr 13ffffc153494b00 by task modprobe/590 | Pointer tag: [13], memory tag: [fe] | | Call trace: | __kasan_report+0x16c/0x1dc | kasan_report+0x10/0x18 | check_memory_region | __hwasan_load1_noabort+0x4c/0x54 | strcmp+0x20/0x64 | create_pinctrl+0x18c/0x7f4 | pinctrl_get+0x90/0x114 | devm_pinctrl_get+0x44/0x98 | pinctrl_bind_pins+0x5c/0x450 | really_probe+0x1c8/0x9a4 | driver_probe_device+0x120/0x1d8 Follow the example of sysfs, and duplicate the device name string before stashing it away in the pinctrl mapping entries. Cc: Linus Walleij Reported-by: Elena Petrova Tested-by: Elena Petrova Signed-off-by: Will Deacon --- drivers/pinctrl/devicetree.c | 25 ++++++++++++++++++++----- 1 file changed, 20 insertions(+), 5 deletions(-) diff --git a/drivers/pinctrl/devicetree.c b/drivers/pinctrl/devicetree.c index 88ddbb2e30de..9721ad30c541 100644 --- a/drivers/pinctrl/devicetree.c +++ b/drivers/pinctrl/devicetree.c @@ -29,6 +29,13 @@ struct pinctrl_dt_map { static void dt_free_map(struct pinctrl_dev *pctldev, struct pinctrl_map *map, unsigned num_maps) { + int i; + + for (i = 0; i < num_maps; ++i) { + kfree_const(map[i].dev_name); + map[i].dev_name = NULL; + } + if (pctldev) { const struct pinctrl_ops *ops = pctldev->desc->pctlops; if (ops->dt_free_map) @@ -63,7 +70,13 @@ static int dt_remember_or_free_map(struct pinctrl *p, const char *statename, /* Initialize common mapping table entry fields */ for (i = 0; i < num_maps; i++) { - map[i].dev_name = dev_name(p->dev); + const char *devname; + + devname = kstrdup_const(dev_name(p->dev), GFP_KERNEL); + if (!devname) + goto err_free_map; + + map[i].dev_name = devname; map[i].name = statename; if (pctldev) map[i].ctrl_dev_name = dev_name(pctldev->dev); @@ -71,10 +84,8 @@ static int dt_remember_or_free_map(struct pinctrl *p, const char *statename, /* Remember the converted mapping table entries */ dt_map = kzalloc(sizeof(*dt_map), GFP_KERNEL); - if (!dt_map) { - dt_free_map(pctldev, map, num_maps); - return -ENOMEM; - } + if (!dt_map) + goto err_free_map; dt_map->pctldev = pctldev; dt_map->map = map; @@ -82,6 +93,10 @@ static int dt_remember_or_free_map(struct pinctrl *p, const char *statename, list_add_tail(&dt_map->node, &p->dt_maps); return pinctrl_register_map(map, num_maps, false); + +err_free_map: + dt_free_map(pctldev, map, num_maps); + return -ENOMEM; } struct pinctrl_dev *of_pinctrl_get(struct device_node *np)