| Message ID | 20220302094353.3465-2-LinoSanfilippo@gmx.de |
|---|---|
| State | Accepted |
| Commit | 7e0438f83dc769465ee663bb5dcf8cc154940712 |
| Headers | show |
| Series | [v9,1/1] tpm: fix reference counting for struct tpm_chip | expand |
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 <l.sanfilippo@kunbus.com> >> >> 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 >> [<c0410c3c>] (unwind_backtrace) from [<c040b580>] (show_stack+0x10/0x14) >> [<c040b580>] (show_stack) from [<c1092174>] (dump_stack+0xc4/0xd8) >> [<c1092174>] (dump_stack) from [<c0445a30>] (__warn+0x104/0x108) >> [<c0445a30>] (__warn) from [<c0445aa8>] (warn_slowpath_fmt+0x74/0xb8) >> [<c0445aa8>] (warn_slowpath_fmt) from [<c08435d0>] (kobject_get+0xa0/0xa4) >> [<c08435d0>] (kobject_get) from [<bf0a715c>] (tpm_try_get_ops+0x14/0x54 [tpm]) >> [<bf0a715c>] (tpm_try_get_ops [tpm]) from [<bf0a7d6c>] (tpm_common_write+0x38/0x60 [tpm]) >> [<bf0a7d6c>] (tpm_common_write [tpm]) from [<c05a7ac0>] (vfs_write+0xc4/0x3c0) >> [<c05a7ac0>] (vfs_write) from [<c05a7ee4>] (ksys_write+0x58/0xcc) >> [<c05a7ee4>] (ksys_write) from [<c04001a0>] (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<n>") >> 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<n>") >> Fixes: 8979b02aaf1d ("tpm: Fix reference count to main device") >> Co-developed-by: Jason Gunthorpe <jgg@ziepe.ca> >> Tested-by: Stefan Berger <stefanb@linux.ibm.com> >> Signed-off-by: Jason Gunthorpe <jgg@ziepe.ca> >> Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de> >> --- >> 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 <jarkko@kernel.org> > > Stefan, if possible, for sanity check, redo test with v9. We need that other patch as well! Tested-by: Stefan Berger <stefanb@linux.ibm.com> Stefan > > BR, Jarkko
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; +}