--- /dev/null
+From 7e0438f83dc769465ee663bb5dcf8cc154940712 Mon Sep 17 00:00:00 2001
+From: Lino Sanfilippo <LinoSanfilippo@gmx.de>
+Date: Wed, 2 Mar 2022 10:43:53 +0100
+Subject: tpm: fix reference counting for struct tpm_chip
+
+From: Lino Sanfilippo <LinoSanfilippo@gmx.de>
+
+commit 7e0438f83dc769465ee663bb5dcf8cc154940712 upstream.
+
+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>
+Signed-off-by: Jason Gunthorpe <jgg@ziepe.ca>
+Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
+Tested-by: Stefan Berger <stefanb@linux.ibm.com>
+Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
+Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
+Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ 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(-)
+
+--- a/drivers/char/tpm/tpm-chip.c
++++ b/drivers/char/tpm/tpm-chip.c
+@@ -274,14 +274,6 @@ static void tpm_dev_release(struct devic
+ 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 d
+ 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 d
+ 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 d
+ 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 tp
+ }
+
+ 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 err_del_cdev;
+ }
+
+ /* Make the chip available. */
+@@ -460,6 +426,10 @@ static int tpm_add_char_device(struct tp
+ 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;
+ }
+
+@@ -649,7 +619,7 @@ void tpm_chip_unregister(struct tpm_chip
+ hwrng_unregister(&chip->hwrng);
+ tpm_bios_log_teardown(chip);
+ if (chip->flags & TPM_CHIP_FLAG_TPM2)
+- cdev_device_del(&chip->cdevs, &chip->devs);
++ tpm_devs_remove(chip);
+ tpm_del_char_device(chip);
+ }
+ EXPORT_SYMBOL_GPL(tpm_chip_unregister);
+--- a/drivers/char/tpm/tpm.h
++++ b/drivers/char/tpm/tpm.h
+@@ -234,6 +234,8 @@ int tpm2_prepare_space(struct tpm_chip *
+ 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);
+--- a/drivers/char/tpm/tpm2-space.c
++++ b/drivers/char/tpm/tpm2-space.c
+@@ -574,3 +574,68 @@ out:
+ 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;
++}
projects / thirdparty / kernel / stable-queue.git / commitdiff
