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=-13.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 286BFC433FC for ; Mon, 20 Jul 2020 15:41:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 077E120773 for ; Mon, 20 Jul 2020 15:41:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595259661; bh=w6ucB/o8IZj1V6Bfp0AHzzz9sx4qou/ANKim26UEEms=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=WVhhqgtdFTBUs1VeCKbZnV3feJPvJBia7vibOFRP3CHThhCLhnubH8SeVwzCgd2d1 7q0SGSnzInJhd2Im4Wl1vKCplgKvHIDQuBBSgbIRfTNStQruv67CgXnnXesrQwWzdt kMVRWNCjzAO0zhOovSDJkiQsDXYi+WAHjqpK7xQ0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729061AbgGTPlA (ORCPT ); Mon, 20 Jul 2020 11:41:00 -0400 Received: from mail.kernel.org ([198.145.29.99]:60584 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729798AbgGTPk4 (ORCPT ); Mon, 20 Jul 2020 11:40:56 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 472372176B; Mon, 20 Jul 2020 15:40:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595259655; bh=w6ucB/o8IZj1V6Bfp0AHzzz9sx4qou/ANKim26UEEms=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ilod017PZ4S9liPyHAaSDZ++TKMu4KV5UgSuvh7ry/2BaLGVfQTrAPwLIQA4iEb7a eK7YXJ7I/rc8lLQhMNSqD248pxRHG2aCgob93mg5X7FmSBP6LJs2MuXhbzgqxM96k2 Om3ZYKgKhhjMzO04tYQz+bvGKu9y4cih8WmqaoPM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Zhenzhong Duan , Mark Brown , Sasha Levin Subject: [PATCH 4.9 04/86] spi: spidev: fix a potential use-after-free in spidev_release() Date: Mon, 20 Jul 2020 17:36:00 +0200 Message-Id: <20200720152753.352510783@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200720152753.138974850@linuxfoundation.org> References: <20200720152753.138974850@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Zhenzhong Duan [ Upstream commit 06096cc6c5a84ced929634b0d79376b94c65a4bd ] If an spi device is unbounded from the driver before the release process, there will be an NULL pointer reference when it's referenced in spi_slave_abort(). Fix it by checking it's already freed before reference. Signed-off-by: Zhenzhong Duan Link: https://lore.kernel.org/r/20200618032125.4650-2-zhenzhong.duan@gmail.com Signed-off-by: Mark Brown Signed-off-by: Sasha Levin --- drivers/spi/spidev.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c index 67ad7e46da42d..c364d9ce6d4b5 100644 --- a/drivers/spi/spidev.c +++ b/drivers/spi/spidev.c @@ -636,15 +636,20 @@ err_find_dev: static int spidev_release(struct inode *inode, struct file *filp) { struct spidev_data *spidev; + int dofree; mutex_lock(&device_list_lock); spidev = filp->private_data; filp->private_data = NULL; + spin_lock_irq(&spidev->spi_lock); + /* ... after we unbound from the underlying device? */ + dofree = (spidev->spi == NULL); + spin_unlock_irq(&spidev->spi_lock); + /* last close? */ spidev->users--; if (!spidev->users) { - int dofree; kfree(spidev->tx_buffer); spidev->tx_buffer = NULL; @@ -652,19 +657,14 @@ static int spidev_release(struct inode *inode, struct file *filp) kfree(spidev->rx_buffer); spidev->rx_buffer = NULL; - spin_lock_irq(&spidev->spi_lock); - if (spidev->spi) - spidev->speed_hz = spidev->spi->max_speed_hz; - - /* ... after we unbound from the underlying device? */ - dofree = (spidev->spi == NULL); - spin_unlock_irq(&spidev->spi_lock); - if (dofree) kfree(spidev); + else + spidev->speed_hz = spidev->spi->max_speed_hz; } #ifdef CONFIG_SPI_SLAVE - spi_slave_abort(spidev->spi); + if (!dofree) + spi_slave_abort(spidev->spi); #endif mutex_unlock(&device_list_lock); -- 2.25.1