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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AD194C433F5 for ; Sat, 5 Mar 2022 05:30:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230180AbiCEFaz (ORCPT ); Sat, 5 Mar 2022 00:30:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57566 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229516AbiCEFaz (ORCPT ); Sat, 5 Mar 2022 00:30:55 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C752413DD8; Fri, 4 Mar 2022 21:30:04 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 5B056B80B20; Sat, 5 Mar 2022 05:30:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 88327C004E1; Sat, 5 Mar 2022 05:30:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646458201; bh=Edc8b81vZYzSpHrCt+tg7zphPi/WO47pgwBOpHM+Tck=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=JF27r+2dwBL7hWFpKfZY2190IhJNPQ5Ham9BXjUoSXQIAg5g0bbnPmmgJrjHf+z99 vu2bn70aoii6JPD+VU0wen8ciLOOLAEaDoODLsTOzqzKj4cib1qVPrI+qLT85gn8yb SLWdS2WVV0kVAtUHmz4q9TTDN7FP6lq4ZV8D1H+GomadWg7P51qQZ59DBpG8AN6Egn ozv4XhnXx0M1mU3vchXSb2p72Fq/dySKZQ+xEq8h79qpahUjW9tNjUl/VXKXcRi6bo y2cwGzOe0Ay1vFNzCpd/CqaUQNwlBE8hKEAoig1yFjfj6ufkaBdur+L9LKInB4z44R TYzgluPL+KGlw== Date: Sat, 5 Mar 2022 07:29:16 +0200 From: Jarkko Sakkinen To: Stefan Berger Cc: Lino Sanfilippo , peterhuewe@gmx.de, jgg@ziepe.ca, stefanb@linux.vnet.ibm.com, James.Bottomley@hansenpartnership.com, David.Laight@aculab.com, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, p.rosenberger@kunbus.com, Lino Sanfilippo , stable@vger.kernel.org Subject: Re: [PATCH v9 1/1] tpm: fix reference counting for struct tpm_chip Message-ID: References: <20220302094353.3465-1-LinoSanfilippo@gmx.de> <20220302094353.3465-2-LinoSanfilippo@gmx.de> <8b594101-f676-ca9d-ebe5-337470a3de80@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On Sat, Mar 05, 2022 at 07:21:26AM +0200, Jarkko Sakkinen wrote: > On Fri, Mar 04, 2022 at 01:34:06PM -0500, Stefan Berger wrote: > > > > On 3/3/22 17:45, Jarkko Sakkinen wrote: > > > On Wed, Mar 02, 2022 at 10:43:53AM +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 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 > > > > Tested-by: Stefan Berger > > > > Signed-off-by: Jason Gunthorpe > > > > Signed-off-by: Lino Sanfilippo > > > > --- > > > > drivers/char/tpm/tpm-chip.c | 46 +++++-------------------- > > > > drivers/char/tpm/tpm.h | 2 ++ > > > > drivers/char/tpm/tpm2-space.c | 65 +++++++++++++++++++++++++++++++++++ > > > > 3 files changed, 75 insertions(+), 38 deletions(-) > > > > > > > > diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c > > > > index b009e7479b70..783d65fc71f0 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; > > > > @@ -352,29 +343,12 @@ 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; > > > > @@ -382,9 +356,7 @@ struct tpm_chip *tpm_chip_alloc(struct device *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 && !tpm_is_firmware_upgrade(chip)) { > > > > - 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 err_del_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; > > > > + > > > > +err_del_cdev: > > > > + cdev_device_del(&chip->cdev, &chip->dev); > > > > return rc; > > > > } > > > > @@ -654,7 +624,7 @@ void tpm_chip_unregister(struct tpm_chip *chip) > > > > hwrng_unregister(&chip->hwrng); > > > > tpm_bios_log_teardown(chip); > > > > if (chip->flags & TPM_CHIP_FLAG_TPM2 && !tpm_is_firmware_upgrade(chip)) > > > > - cdev_device_del(&chip->cdevs, &chip->devs); > > > > + tpm_devs_remove(chip); > > > > 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 283f78211c3a..2163c6ee0d36 100644 > > > > --- a/drivers/char/tpm/tpm.h > > > > +++ b/drivers/char/tpm/tpm.h > > > > @@ -234,6 +234,8 @@ 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_devs_remove(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 97e916856cf3..265ec72b1d81 100644 > > > > --- a/drivers/char/tpm/tpm2-space.c > > > > +++ b/drivers/char/tpm/tpm2-space.c > > > > @@ -574,3 +574,68 @@ 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); > > > > +} > > > > + > > > > +/* > > > > + * Remove the device file for exposed TPM spaces and release the device > > > > + * reference. This may also release the reference to the master device. > > > > + */ > > > > +void tpm_devs_remove(struct tpm_chip *chip) > > > > +{ > > > > + cdev_device_del(&chip->cdevs, &chip->devs); > > > > + put_device(&chip->devs); > > > > +} > > > > + > > > > +/* > > > > + * 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 err_put_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 err_put_devs; > > > > + } > > > > + > > > > + return 0; > > > > + > > > > +err_put_devs: > > > > + put_device(&chip->devs); > > > > + > > > > + return rc; > > > > +} > > > > -- > > > > 2.35.1 > > > > > > > LGTM, thank you. > > > > > > Reviewed-by: Jarkko Sakkinen > > > > > > Stefan, if possible, for sanity check, redo test with v9. > > > > We need that other patch as well! > > Yes. > > > Tested-by: Stefan Berger > > Thank you. I fixed this manually: $ scripts/checkpatch.pl 0001-tpm-fix-reference-counting-for-struct-tpm_chip.patch WARNING: From:/Signed-off-by: email address mismatch: 'From: Lino Sanfilippo ' != 'Signed-off-by: Lino Sanfilippo ' Changed "From:" to sob address. It's now in git://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd.git and should appear to linux-next. BR, Jarkko