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=-16.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 9917EC43381 for ; Fri, 5 Feb 2021 06:52:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5B94E64DD6 for ; Fri, 5 Feb 2021 06:52:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231302AbhBEGwH (ORCPT ); Fri, 5 Feb 2021 01:52:07 -0500 Received: from mail.kernel.org ([198.145.29.99]:56538 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230483AbhBEGvh (ORCPT ); Fri, 5 Feb 2021 01:51:37 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4001564F9C; Fri, 5 Feb 2021 06:50:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1612507856; bh=941AkqL1nii7c/B1BmKXvFA4vyQEem3CqwJZMXTjS/U=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Vge0txLvFe19JT7T9lI/ExzG2SxjlRjRPGpgidOS9ldJFIZ/Z5LgQtn445V11NVrJ MTR6Cqk6lFYHaUWCNDcn1amOouaiDQqtgJfV1X3apgjnE1QhLffvQhD0Pp1/qFr1UJ YZVYf9f3lwc9sxOdzDA9nL5i5pEeL9azUiSmjy+k= Date: Fri, 5 Feb 2021 07:50:54 +0100 From: Greg KH To: Lino Sanfilippo Cc: peterhuewe@gmx.de, jarkko@kernel.org, jgg@ziepe.ca, stefanb@linux.vnet.ibm.com, James.Bottomley@hansenpartnership.com, stable@vger.kernel.org, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, Lino Sanfilippo Subject: Re: [PATCH v3 1/2] tpm: fix reference counting for struct tpm_chip Message-ID: References: <1612482643-11796-1-git-send-email-LinoSanfilippo@gmx.de> <1612482643-11796-2-git-send-email-LinoSanfilippo@gmx.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1612482643-11796-2-git-send-email-LinoSanfilippo@gmx.de> Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On Fri, Feb 05, 2021 at 12:50:42AM +0100, Lino Sanfilippo wrote: > From: Lino Sanfilippo > > The following sequence of operations results in a refcount warning: > > 1. Open device /dev/tpmrm > 2. Remove module tpm_tis_spi > 3. Write a TPM command to the file descriptor opened at step 1. > > ------------[ cut here ]------------ > WARNING: CPU: 3 PID: 1161 at lib/refcount.c:25 kobject_get+0xa0/0xa4 > refcount_t: addition on 0; use-after-free. > Modules linked in: tpm_tis_spi tpm_tis_core tpm mdio_bcm_unimac brcmfmac > sha256_generic libsha256 sha256_arm hci_uart btbcm bluetooth cfg80211 vc4 > brcmutil ecdh_generic ecc snd_soc_core crc32_arm_ce libaes > raspberrypi_hwmon ac97_bus snd_pcm_dmaengine bcm2711_thermal snd_pcm > snd_timer genet snd phy_generic soundcore [last unloaded: spi_bcm2835] > CPU: 3 PID: 1161 Comm: hold_open Not tainted 5.10.0ls-main-dirty #2 > Hardware name: BCM2711 > [] (unwind_backtrace) from [] (show_stack+0x10/0x14) > [] (show_stack) from [] (dump_stack+0xc4/0xd8) > [] (dump_stack) from [] (__warn+0x104/0x108) > [] (__warn) from [] (warn_slowpath_fmt+0x74/0xb8) > [] (warn_slowpath_fmt) from [] (kobject_get+0xa0/0xa4) > [] (kobject_get) from [] (tpm_try_get_ops+0x14/0x54 [tpm]) > [] (tpm_try_get_ops [tpm]) from [] (tpm_common_write+0x38/0x60 [tpm]) > [] (tpm_common_write [tpm]) from [] (vfs_write+0xc4/0x3c0) > [] (vfs_write) from [] (ksys_write+0x58/0xcc) > [] (ksys_write) from [] (ret_fast_syscall+0x0/0x4c) > Exception stack(0xc226bfa8 to 0xc226bff0) > bfa0: 00000000 000105b4 00000003 beafe664 00000014 00000000 > bfc0: 00000000 000105b4 000103f8 00000004 00000000 00000000 b6f9c000 beafe684 > bfe0: 0000006c beafe648 0001056c b6eb6944 > ---[ end trace d4b8409def9b8b1f ]--- > > The reason for this warning is the attempt to get the chip->dev reference > in tpm_common_write() although the reference counter is already zero. > > Since commit 8979b02aaf1d ("tpm: Fix reference count to main device") the > extra reference used to prevent a premature zero counter is never taken, > because the required TPM_CHIP_FLAG_TPM2 flag is never set. > > Fix this by removing the flag condition. > > Commit fdc915f7f719 ("tpm: expose spaces via a device link /dev/tpmrm") > already introduced function tpm_devs_release() to release the extra > reference but did not implement the required put on chip->devs that results > in the call of this function. > > Fix this also by installing an action handler that puts chip->devs as soon > as the chip is unregistered. > > Fixes: fdc915f7f719 ("tpm: expose spaces via a device link /dev/tpmrm") > Fixes: 8979b02aaf1d ("tpm: Fix reference count to main device") > Signed-off-by: Lino Sanfilippo > --- > drivers/char/tpm/tpm-chip.c | 18 +++++++++++++++--- > drivers/char/tpm/tpm_ftpm_tee.c | 2 ++ > drivers/char/tpm/tpm_vtpm_proxy.c | 1 + > 3 files changed, 18 insertions(+), 3 deletions(-) This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read: https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html for how to do this properly.