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=-10.4 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 BD528C433DB for ; Fri, 5 Feb 2021 01:46:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 738AF64E16 for ; Fri, 5 Feb 2021 01:46:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232944AbhBEBpv (ORCPT ); Thu, 4 Feb 2021 20:45:51 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:58750 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S232903AbhBEBpk (ORCPT ); Thu, 4 Feb 2021 20:45:40 -0500 Received: from pps.filterd (m0098419.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 1151W82i131075; Thu, 4 Feb 2021 20:44:50 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=subject : from : to : cc : references : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=pp1; bh=TIEb3+afSV3AJbVcVj/P0BfDKRQCY1YSyX9SgNW3ix4=; b=dDwHotrsSF5VvqV7PvsYKvUULl87DICuO2j769V0giKVCm0n/FFSRkWcFVOmnbZD0pEG mgoMzSo73iCEavkOydmh0jVC/u6fEr+mu1revCIiOS/hjvpzyxRSRDKbeLx7HvHODQrE Qy+QSarLno+gEEM+VK5H6tpVmCEwbZFvlU1Set/FUVClaSL6kdXW65WP0nUaQ3drHHW3 7eUlXWFJ3FgActOnkTvK31lNFqnbB+ZWlf5zAD6Dv8178IxNi1rz8tw2IpIXYRDVpL9I xdeZqhiCSjPENUoVrewTy4JPtRYFZPNhuSJYpTBHnnkmjy+uu8vZS22PcrDva+eODVgN Dw== Received: from pps.reinject (localhost [127.0.0.1]) by mx0b-001b2d01.pphosted.com with ESMTP id 36guxxgvsg-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 04 Feb 2021 20:44:50 -0500 Received: from m0098419.ppops.net (m0098419.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.36/8.16.0.36) with SMTP id 1151WKjL131535; Thu, 4 Feb 2021 20:44:50 -0500 Received: from ppma03wdc.us.ibm.com (ba.79.3fa9.ip4.static.sl-reverse.com [169.63.121.186]) by mx0b-001b2d01.pphosted.com with ESMTP id 36guxxgvs8-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 04 Feb 2021 20:44:50 -0500 Received: from pps.filterd (ppma03wdc.us.ibm.com [127.0.0.1]) by ppma03wdc.us.ibm.com (8.16.0.42/8.16.0.42) with SMTP id 1151gBbG011914; Fri, 5 Feb 2021 01:44:49 GMT Received: from b01cxnp22035.gho.pok.ibm.com (b01cxnp22035.gho.pok.ibm.com [9.57.198.25]) by ppma03wdc.us.ibm.com with ESMTP id 36f2nxehg1-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 05 Feb 2021 01:44:49 +0000 Received: from b01ledav002.gho.pok.ibm.com (b01ledav002.gho.pok.ibm.com [9.57.199.107]) by b01cxnp22035.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 1151inLB26018076 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 5 Feb 2021 01:44:49 GMT Received: from b01ledav002.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 41681124054; Fri, 5 Feb 2021 01:44:49 +0000 (GMT) Received: from b01ledav002.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2B35A124053; Fri, 5 Feb 2021 01:44:49 +0000 (GMT) Received: from sbct-3.pok.ibm.com (unknown [9.47.158.153]) by b01ledav002.gho.pok.ibm.com (Postfix) with ESMTP; Fri, 5 Feb 2021 01:44:49 +0000 (GMT) Subject: Re: [PATCH v3 1/2] tpm: fix reference counting for struct tpm_chip From: Stefan Berger To: Lino Sanfilippo , peterhuewe@gmx.de, jarkko@kernel.org Cc: 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 References: <1612482643-11796-1-git-send-email-LinoSanfilippo@gmx.de> <1612482643-11796-2-git-send-email-LinoSanfilippo@gmx.de> Message-ID: Date: Thu, 4 Feb 2021 20:44:48 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.369,18.0.737 definitions=2021-02-04_13:2021-02-04,2021-02-04 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 clxscore=1015 suspectscore=0 adultscore=0 impostorscore=0 spamscore=0 phishscore=0 mlxlogscore=999 priorityscore=1501 malwarescore=0 bulkscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2102050002 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/4/21 7:46 PM, Stefan Berger wrote: > On 2/4/21 6:50 PM, 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 > > Tested-by: Stefan Berger > > Steps: > > modprobe tpm_vtpm_proxy > > swtpm chardev --vtpm-proxy --tpm2 --tpmstate dir=./ & > > exec 100<>/dev/tpmrm1 > > kill -9 > > rmmod tpm_vtpm_proxy > > exec 100>&-   # fails before, works after   --> great job! :-) > > To clarify: When I tested this I had *both* patches applied. Without the patches I got the null pointer exception in tpm2_del_space(). The 2nd patch alone solves that issue when using the steps above. [  525.647443] [c000000005d3bba0] [c000000000e81d78] mutex_lock+0x28/0x90 (unreliable) [  525.647539] [c000000005d3bbd0] [c0080000001f5da0] tpm2_del_space+0x48/0x130 [tpm] [  525.647635] [c000000005d3bc20] [c0080000001f56b8] tpmrm_release+0x40/0x70 [tpm] [  525.647746] [c000000005d3bc50] [c0000000004bf718] __fput+0xb8/0x340 [  525.647842] [c000000005d3bca0] [c00000000017def4] task_work_run+0xe4/0x150 [  525.647930] [c000000005d3bcf0] [c00000000001feb4] do_notify_resume+0x484/0x4f0 [  525.648023] [c000000005d3bdb0] [c000000000033a64] syscall_exit_prepare+0x1d4/0x330 [  525.648115] [c000000005d3be20] [c00000000000d96c] system_call_common+0xfc/0x27c