From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A2B9AC282C8 for ; Mon, 28 Jan 2019 17:52:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7135420881 for ; Mon, 28 Jan 2019 17:52:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548697954; bh=UaU2v9q9c1g8rto2aM2CQUEMVCf4hkrzL06mthyZTik=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Tr/5hmrAzDlyb413cNNh2Hx0Uf/xhDvjhy6nKTB6E6kpuR8kTZy8o7O8CfeB4o9TM xJLcPG0EXCPf+M5DBO8eBOlfZqgqoeLwfkNCXzZ61eiLTRHbNRBwX65jlStwt26oaE 3RIt1+s0i9RVAnlkarzw4iydTbtcmIksRTLZafXE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727785AbfA1Rwd (ORCPT ); Mon, 28 Jan 2019 12:52:33 -0500 Received: from mail.kernel.org ([198.145.29.99]:57052 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727066AbfA1Pnw (ORCPT ); Mon, 28 Jan 2019 10:43:52 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (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 547582175B; Mon, 28 Jan 2019 15:43:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548690231; bh=UaU2v9q9c1g8rto2aM2CQUEMVCf4hkrzL06mthyZTik=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uwIYFsnMNgg7q7pbpnppuF/VxtsGqGkyUAHzUdY5ty4XA8G/7ZiLsasgAjuxq3e8+ uVnninDFZP/7Kr962estvB75qhT7gpijqazb56u9xxt9iUJGCNmyj0ItrqytZE5eSH 6saUx4M60xzyoIWlqA1YT26m9e6yL4GgickaasWE= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Muchun Song , Linus Walleij , Sasha Levin Subject: [PATCH AUTOSEL 4.20 008/304] gpiolib: Fix possible use after free on label Date: Mon, 28 Jan 2019 10:38:45 -0500 Message-Id: <20190128154341.47195-8-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190128154341.47195-1-sashal@kernel.org> References: <20190128154341.47195-1-sashal@kernel.org> MIME-Version: 1.0 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Muchun Song [ Upstream commit 18534df419041e6c1f4b41af56ee7d41f757815c ] gpiod_request_commit() copies the pointer to the label passed as an argument only to be used later. But there's a chance the caller could immediately free the passed string(e.g., local variable). This could trigger a use after free when we use gpio label(e.g., gpiochip_unlock_as_irq(), gpiochip_is_requested()). To be on the safe side: duplicate the string with kstrdup_const() so that if an unaware user passes an address to a stack-allocated buffer, we won't get the arbitrary label. Also fix gpiod_set_consumer_name(). Signed-off-by: Muchun Song Signed-off-by: Linus Walleij Signed-off-by: Sasha Levin --- drivers/gpio/gpiolib.c | 25 +++++++++++++++++++++---- include/linux/gpio/consumer.h | 6 ++++-- 2 files changed, 25 insertions(+), 6 deletions(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index a2cbb474901c..33266460e81c 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -2299,6 +2299,12 @@ static int gpiod_request_commit(struct gpio_desc *desc, const char *label) unsigned long flags; unsigned offset; + if (label) { + label = kstrdup_const(label, GFP_KERNEL); + if (!label) + return -ENOMEM; + } + spin_lock_irqsave(&gpio_lock, flags); /* NOTE: gpio_request() can be called in early boot, @@ -2309,6 +2315,7 @@ static int gpiod_request_commit(struct gpio_desc *desc, const char *label) desc_set_label(desc, label ? : "?"); status = 0; } else { + kfree_const(label); status = -EBUSY; goto done; } @@ -2325,6 +2332,7 @@ static int gpiod_request_commit(struct gpio_desc *desc, const char *label) if (status < 0) { desc_set_label(desc, NULL); + kfree_const(label); clear_bit(FLAG_REQUESTED, &desc->flags); goto done; } @@ -2420,6 +2428,7 @@ static bool gpiod_free_commit(struct gpio_desc *desc) chip->free(chip, gpio_chip_hwgpio(desc)); spin_lock_irqsave(&gpio_lock, flags); } + kfree_const(desc->label); desc_set_label(desc, NULL); clear_bit(FLAG_ACTIVE_LOW, &desc->flags); clear_bit(FLAG_REQUESTED, &desc->flags); @@ -3375,11 +3384,19 @@ EXPORT_SYMBOL_GPL(gpiod_cansleep); * @desc: gpio to set the consumer name on * @name: the new consumer name */ -void gpiod_set_consumer_name(struct gpio_desc *desc, const char *name) +int gpiod_set_consumer_name(struct gpio_desc *desc, const char *name) { - VALIDATE_DESC_VOID(desc); - /* Just overwrite whatever the previous name was */ - desc->label = name; + VALIDATE_DESC(desc); + if (name) { + name = kstrdup_const(name, GFP_KERNEL); + if (!name) + return -ENOMEM; + } + + kfree_const(desc->label); + desc_set_label(desc, name); + + return 0; } EXPORT_SYMBOL_GPL(gpiod_set_consumer_name); diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h index f2f887795d43..ed070512b40e 100644 --- a/include/linux/gpio/consumer.h +++ b/include/linux/gpio/consumer.h @@ -162,7 +162,7 @@ int gpiod_is_active_low(const struct gpio_desc *desc); int gpiod_cansleep(const struct gpio_desc *desc); int gpiod_to_irq(const struct gpio_desc *desc); -void gpiod_set_consumer_name(struct gpio_desc *desc, const char *name); +int gpiod_set_consumer_name(struct gpio_desc *desc, const char *name); /* Convert between the old gpio_ and new gpiod_ interfaces */ struct gpio_desc *gpio_to_desc(unsigned gpio); @@ -495,10 +495,12 @@ static inline int gpiod_to_irq(const struct gpio_desc *desc) return -EINVAL; } -static inline void gpiod_set_consumer_name(struct gpio_desc *desc, const char *name) +static inline int gpiod_set_consumer_name(struct gpio_desc *desc, + const char *name) { /* GPIO can never have been requested */ WARN_ON(1); + return -EINVAL; } static inline struct gpio_desc *gpio_to_desc(unsigned gpio) -- 2.19.1