From patchwork Wed Mar 2 09:43:53 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lino Sanfilippo X-Patchwork-Id: 12765696 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 3B51CC433F5 for ; Wed, 2 Mar 2022 09:45:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239566AbiCBJpp (ORCPT ); Wed, 2 Mar 2022 04:45:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45838 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236773AbiCBJpl (ORCPT ); Wed, 2 Mar 2022 04:45:41 -0500 Received: from mout.gmx.net (mout.gmx.net [212.227.15.19]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1D0363EF0F; Wed, 2 Mar 2022 01:44:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1646214281; bh=C6KNp58WJw25Gqq/g2x7bv1Z1SERyWZpCzd+LWYptzA=; h=X-UI-Sender-Class:From:To:Cc:Subject:Date:In-Reply-To:References; b=PhEWgWthBFzxP/57lZlD6JQh2tCROKVGmBNuC+6J0MC/AbmySq5uupn8IZB5G8tDD uP4ZhPfEcTyuy4ngS+YhdJKE1hgE73dx+PzX2A9qKiL9YCQB6bBX9mNWREEHS06DFH aEA3Hxy6s/qgCa3rU8G1XpLFny8/tYNGeCP0dz/0= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from Venus.fritz.box ([149.172.237.68]) by mail.gmx.net (mrgmx004 [212.227.17.190]) with ESMTPSA (Nemesis) id 1MMXUD-1nf5XL2v1r-00JZGr; Wed, 02 Mar 2022 10:44:40 +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, p.rosenberger@kunbus.com, LinoSanfilippo@gmx.de, Lino Sanfilippo , stable@vger.kernel.org, Stefan Berger Subject: [PATCH v9 1/1] tpm: fix reference counting for struct tpm_chip Date: Wed, 2 Mar 2022 10:43:53 +0100 Message-Id: <20220302094353.3465-2-LinoSanfilippo@gmx.de> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220302094353.3465-1-LinoSanfilippo@gmx.de> References: <20220302094353.3465-1-LinoSanfilippo@gmx.de> MIME-Version: 1.0 X-Provags-ID: V03:K1:Hq0i+WnnfUA1Teyrfoie5syUK83shLkeKoo68IkBwnsRRnHmIUk EJbXKrWqkArbObL6i7P2++Fqj/APE/sJP04xhN9Mz5lUh+G9Ob3u1QMXXM6eu9W2KsjOngV aiRV+6dCktplJxsaSHe+Zv2ebOpJ1pvi78sEZzi0e1O0Ktq4nfypNpM+DdCV8rQQ8FHT9t1 E1wvD1yDoTHdDgjvAA+EQ== X-UI-Out-Filterresults: notjunk:1;V03:K0:gQ90RZuDlS8=:eBRPdeAJQ/d8vjvV6b7tMD BwM/JuNkirWvMBSm48Aakq1iYiY9yRNv1Oy8iNGuMuusH+19i9zX7+L4NwQrGX9QrZ/fPUCWA OfwQdZkOLuJ3iGx+gHAo1cd4T29kOad8uA+yTOkR+xzmF04kIvSkR8hv4iQCXuZs4/b1/4iYR v5N/mOgdpS/l5s9e0J18byU76n9eUevLJW8aXPX94N82LCodu5/KNq3zCwPP3Ipx+50ztmzQ7 0E//gD0tlYwnSAT3wcUy2yRk/dXw2NBaUIDtZYKHEU7own9hEkWZwaWRoWEohKl1YOKAT7Wqa gtANJtEheW4ALxHwRysg0gp/VnPKGrQb4KPdC27OedMlP40N86n/zyCjyBmpeK+d259FkQMOj 1lNzTOZYxe9uWBxeYBoJeEfU/dH4qdc2i/6w3+PmLriiPppOt8llNyKbuQsHmPaeTX0plGHS5 4FnMEpAgZm8V8+TsjVbaAuG/Mvl5m5NDUc9Mk6vJ8lWc0Q0dQxhIE/6ilf68gJ6yyxGZnem6T USiL0Dpkv76WvISbrlzTxn1bAHYwjHjj0YBS2PFDmECKrHW+Ubsul+xSejw0NdLeDZiPgrA67 K/A6NuzvWKUtTnrCvafoeLGCcDW9ZZpy3OGM0IE6Ryw2+1fbr8yupFa1lSKPfpxS4qvC7quIE +gdcRVG6owT6WAzUqWZSIypWu7q0eKwykCT46P2cHkT4cnQA2ItFMavenBJ+PghA+d5G+KiRV 3xHG/02ED6B+ZAvfJxs3f2MRUETqpml/BU/pPzPhoSOEWDVSfpgq3jUJX8CQit4NPsqvw9Ti4 ZE1y03hAOT0/pvUiTOt4hOpC2MmgUWDNI0pEage3ArjTLX2FhwthisqNfrZlB9nszl4e4tOsI GSnkYdfArqN1guY0a37zhgQJooUO5JQVcfn+bzqxtrp8NbV9m1QwP0cKPJI5CZAGTM1sA4Gs/ 4CzR+Uf9hcFT+w42dcU2ASHSZOERdZcA3gjhazdnriKMihmwl9L6uv7LQpt5YVhTCzKFDzHFy wWZNS8QgyPi6OKtNG+6XpQSOwLmRbJ8m5Pwp36MWGPJtiOrYDTI9DZermsyl4vfAfvkFGxfvw zG47yImBfilk4U= 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 Tested-by: Stefan Berger Signed-off-by: Jason Gunthorpe Signed-off-by: Lino Sanfilippo Reviewed-by: Jarkko Sakkinen Reviewed-by: Jason Gunthorpe Tested-by: Stefan Berger --- 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; +}