From patchwork Sun Feb 21 23:19:27 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lino Sanfilippo X-Patchwork-Id: 12097771 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=-12.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MIME_BASE64_TEXT,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 3818AC433E0 for ; Sun, 21 Feb 2021 23:22:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E75E764E57 for ; Sun, 21 Feb 2021 23:22:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233505AbhBUXV7 (ORCPT ); Sun, 21 Feb 2021 18:21:59 -0500 Received: from mout.gmx.net ([212.227.15.18]:43131 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233476AbhBUXVv (ORCPT ); Sun, 21 Feb 2021 18:21:51 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1613949604; bh=zEEEDewv0P8nasYDAT0RgWZWX4ouDnxZp+NVT6iZs7I=; h=X-UI-Sender-Class:From:To:Cc:Subject:Date:In-Reply-To:References; b=XBtgnTxLVTrSRVquU7QVApk3CLPLzN8dpq1Wr5uueX/BVGTUdNzyxnbi7//YmIY2c x8/5199OqbL8SB4eueKVnVzK77NC4qNxPyd/tlZhEdRSQczrxmAU/TkjATI+zXRD6S rCv/mFFePirRLOJQi3zScoyo01cfNUywPIXE7bJg= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from Venus.fritz.box ([78.42.220.31]) by mail.gmx.net (mrgmx004 [212.227.17.190]) with ESMTPSA (Nemesis) id 1MBDjA-1l7sPF3iIw-00CfMA; Mon, 22 Feb 2021 00:20:04 +0100 From: Lino Sanfilippo To: peterhuewe@gmx.de, jarkko@kernel.org, jgg@ziepe.ca Cc: stefanb@linux.vnet.ibm.com, James.Bottomley@hansenpartnership.com, David.Laight@ACULAB.COM, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, LinoSanfilippo@gmx.de, Lino Sanfilippo , stable@vger.kernel.org Subject: [PATCH v7] tpm: fix reference counting for struct tpm_chip Date: Mon, 22 Feb 2021 00:19:27 +0100 Message-Id: <1613949567-1181-2-git-send-email-LinoSanfilippo@gmx.de> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1613949567-1181-1-git-send-email-LinoSanfilippo@gmx.de> References: <1613949567-1181-1-git-send-email-LinoSanfilippo@gmx.de> MIME-Version: 1.0 X-Provags-ID: V03:K1:DfmZP+vb/vl2fUiJDJYDcOkeBJ80clEd4FGsHGEDR6sGNAXyNLP YDVP230WrOHkcwxfbSuESytB0bETjgCG1rE+1BVTO/+O30e4lHtvp/KgSfgBVEQkK6tbEdd Yzekq56AV3iaAs4dZgJgyN/cjIC+OPzNhZ5JTlNEXtAB1tkz/tWy9EUlEdGmiemkzarcyMh bhgdBUlkcjiiidvRQSasQ== X-UI-Out-Filterresults: notjunk:1;V03:K0:QN+xKuFQoaY=:hbL4+1Tomz5neqzGHnD+3m XwBukrp1NAGIfo370CPX1rHDCdRRucXbwlvBxM+YC4snkgVZA5cKdTJIrGsp9u2WyLsFxx4rt /aFUwQETMp7kCMECA2HGx8gW7qmEbM/z8ke8mXJxFNcpBJ1Sbfh636fvXm7XJ2rJQMjK+BgkU hBdNK+eWkgMQjlgiPoQCfMx3h0s/vNUmIpMHfCBA8EF2yU6tCi2+uNR2PrJhSbcKxJeLwDQnD Tj0hmiJVZbs0PIWvDGR4SIHvMplQgv5J8E8ZCWZdZyUzTTNsILVrRyqePt2eM9m68yhkOoCE+ pI00prhlxTXvZEJd9Y5xfiPKAAmsb818FHxXELoyOW4JK6hZ5X/ZFnqFVh6NkGtLGCwY7QSaW WW9iA+ufWuh/DPj0GBHyW78Cc01jyyibQmDPV6wFBdk9ud+Y4BaKCvR/V0QSWAIoaSTRW7bHy pjX2VofuEVtWAYD7VA7c4+XrOQyXNYUAYARjjOKhCM9fBq7nVPT/B0dqSRzypEPhdw+ZFmxoH tuAgxNbqGJl3HVLV1T45aKaqjEDubPF5D9Da7KzoOcZfXfVvXnn+9s0KnddP2rvFi+uBCPea0 JlSpiLuw9R9IrGIcjYKewwbvz5Es0k+DR5LkEtNLXbUqAufCgseyMFD3RKbyTk6RGP5OeLbcA 1BdjXUg4FMffkRwLGFr+MMNtVOGvIfMtBgW0Fmj6q3dslR/kUMV/KhfeSSGXGi5yW+IspKbNT BPbii+K7VHzor51y0wX3WtoUBwV81W0zPyHJ3w4MmwZ78FS6qqiS9hVndQgcPuyPH2iocACSu mgwS2WIKcHuPGqvK7myq0wlIjGoEJco9ORbkqDsTNxYiS7NDSTh6JjxbJ+i66+iuPkVVv+uwI Qc0h0/N49jALxapUl2Mw== Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org 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 moving the TPM 2 character device handling from tpm_chip_alloc() to tpm_add_char_device() which is called at a later point in time when the flag has been set in case of TPM2. 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 by putting chip->devs in tpm_chip_unregister(). Finally move the new implementation for the TPM 2 handling into a new function to avoid multiple checks for the TPM_CHIP_FLAG_TPM2 flag in the good case and error cases. Cc: stable@vger.kernel.org Fixes: fdc915f7f719 ("tpm: expose spaces via a device link /dev/tpmrm") Fixes: 8979b02aaf1d ("tpm: Fix reference count to main device") Co-developed-by: Jason Gunthorpe Signed-off-by: Jason Gunthorpe Signed-off-by: Lino Sanfilippo --- drivers/char/tpm/tpm-chip.c | 48 ++++++++----------------------------- drivers/char/tpm/tpm.h | 1 + drivers/char/tpm/tpm2-space.c | 55 +++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 66 insertions(+), 38 deletions(-) diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c index ddaeceb..3f59f09 100644 --- a/drivers/char/tpm/tpm-chip.c +++ b/drivers/char/tpm/tpm-chip.c @@ -274,14 +274,6 @@ static void tpm_dev_release(struct device *dev) kfree(chip); } -static void tpm_devs_release(struct device *dev) -{ - struct tpm_chip *chip = container_of(dev, struct tpm_chip, devs); - - /* release the master device reference */ - put_device(&chip->dev); -} - /** * tpm_class_shutdown() - prepare the TPM device for loss of power. * @dev: device to which the chip is associated. @@ -344,7 +336,6 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev, chip->dev_num = rc; device_initialize(&chip->dev); - device_initialize(&chip->devs); chip->dev.class = tpm_class; chip->dev.class->shutdown_pre = tpm_class_shutdown; @@ -352,39 +343,20 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev, chip->dev.parent = pdev; chip->dev.groups = chip->groups; - chip->devs.parent = pdev; - chip->devs.class = tpmrm_class; - chip->devs.release = tpm_devs_release; - /* get extra reference on main device to hold on - * behalf of devs. This holds the chip structure - * while cdevs is in use. The corresponding put - * is in the tpm_devs_release (TPM2 only) - */ - if (chip->flags & TPM_CHIP_FLAG_TPM2) - get_device(&chip->dev); - if (chip->dev_num == 0) chip->dev.devt = MKDEV(MISC_MAJOR, TPM_MINOR); else chip->dev.devt = MKDEV(MAJOR(tpm_devt), chip->dev_num); - chip->devs.devt = - MKDEV(MAJOR(tpm_devt), chip->dev_num + TPM_NUM_DEVICES); - rc = dev_set_name(&chip->dev, "tpm%d", chip->dev_num); if (rc) goto out; - rc = dev_set_name(&chip->devs, "tpmrm%d", chip->dev_num); - if (rc) - goto out; if (!pdev) chip->flags |= TPM_CHIP_FLAG_VIRTUAL; cdev_init(&chip->cdev, &tpm_fops); - cdev_init(&chip->cdevs, &tpmrm_fops); chip->cdev.owner = THIS_MODULE; - chip->cdevs.owner = THIS_MODULE; rc = tpm2_init_space(&chip->work_space, TPM2_SPACE_BUFFER_SIZE); if (rc) { @@ -396,7 +368,6 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev, return chip; out: - put_device(&chip->devs); put_device(&chip->dev); return ERR_PTR(rc); } @@ -445,14 +416,9 @@ static int tpm_add_char_device(struct tpm_chip *chip) } if (chip->flags & TPM_CHIP_FLAG_TPM2) { - rc = cdev_device_add(&chip->cdevs, &chip->devs); - if (rc) { - dev_err(&chip->devs, - "unable to cdev_device_add() %s, major %d, minor %d, err=%d\n", - dev_name(&chip->devs), MAJOR(chip->devs.devt), - MINOR(chip->devs.devt), rc); - return rc; - } + rc = tpm_devs_add(chip); + if (rc) + goto out_cdev; } /* Make the chip available. */ @@ -460,6 +426,10 @@ static int tpm_add_char_device(struct tpm_chip *chip) idr_replace(&dev_nums_idr, chip, chip->dev_num); mutex_unlock(&idr_lock); + return 0; + +out_cdev: + cdev_device_del(&chip->cdev, &chip->dev); return rc; } @@ -640,8 +610,10 @@ void tpm_chip_unregister(struct tpm_chip *chip) if (IS_ENABLED(CONFIG_HW_RANDOM_TPM)) hwrng_unregister(&chip->hwrng); tpm_bios_log_teardown(chip); - if (chip->flags & TPM_CHIP_FLAG_TPM2) + if (chip->flags & TPM_CHIP_FLAG_TPM2) { cdev_device_del(&chip->cdevs, &chip->devs); + put_device(&chip->devs); + } tpm_del_char_device(chip); } EXPORT_SYMBOL_GPL(tpm_chip_unregister); diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h index 947d1db..ac4b2dc 100644 --- a/drivers/char/tpm/tpm.h +++ b/drivers/char/tpm/tpm.h @@ -238,6 +238,7 @@ int tpm2_prepare_space(struct tpm_chip *chip, struct tpm_space *space, u8 *cmd, size_t cmdsiz); int tpm2_commit_space(struct tpm_chip *chip, struct tpm_space *space, void *buf, size_t *bufsiz); +int tpm_devs_add(struct tpm_chip *chip); void tpm_bios_log_setup(struct tpm_chip *chip); void tpm_bios_log_teardown(struct tpm_chip *chip); diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c index 784b8b3..2f8bb3e 100644 --- a/drivers/char/tpm/tpm2-space.c +++ b/drivers/char/tpm/tpm2-space.c @@ -571,3 +571,58 @@ int tpm2_commit_space(struct tpm_chip *chip, struct tpm_space *space, dev_err(&chip->dev, "%s: error %d\n", __func__, rc); return rc; } + +/* + * Put the reference to the main device. + */ +static void tpm_devs_release(struct device *dev) +{ + struct tpm_chip *chip = container_of(dev, struct tpm_chip, devs); + + /* release the master device reference */ + put_device(&chip->dev); +} + +/* + * Add a device file to expose TPM spaces. Also take a reference to the + * main device. + */ +int tpm_devs_add(struct tpm_chip *chip) +{ + int rc; + + device_initialize(&chip->devs); + chip->devs.parent = chip->dev.parent; + chip->devs.class = tpmrm_class; + + /* + * Get extra reference on main device to hold on behalf of devs. + * This holds the chip structure while cdevs is in use. The + * corresponding put is in the tpm_devs_release. + */ + get_device(&chip->dev); + chip->devs.release = tpm_devs_release; + chip->devs.devt = MKDEV(MAJOR(tpm_devt), chip->dev_num + TPM_NUM_DEVICES); + cdev_init(&chip->cdevs, &tpmrm_fops); + chip->cdevs.owner = THIS_MODULE; + + rc = dev_set_name(&chip->devs, "tpmrm%d", chip->dev_num); + if (rc) + goto out_devs; + + rc = cdev_device_add(&chip->cdevs, &chip->devs); + if (rc) { + dev_err(&chip->devs, + "unable to cdev_device_add() %s, major %d, minor %d, err=%d\n", + dev_name(&chip->devs), MAJOR(chip->devs.devt), + MINOR(chip->devs.devt), rc); + goto out_devs; + } + + return 0; + +out_devs: + put_device(&chip->devs); + + return rc; +}