This patch fixes a reference count issue in the TPM core code. It is based
on a suggestion and basic implementation made by Jason Gunthorpe.
Changes in v4:
- drop patch 2 (tpm: in tpm2_del_space check if ops pointer is still
valid) since James Bottomley offered a cleaner solution for this
- reimplement patch 1 to setup the /dev/tpmrm device only in case of TPM2
and avoid the installation of another action handler
- add proper tag for stable
Changes in v3:
- drop the patch that introduces the new function tpm_chip_free()
- rework the commit messages for the patches (style, typos, etc.)
- add fixes tag to patch 2
- add James Bottomley to cc list
- add stable mailing list to cc list
Changes in v2:
- drop the patch that erroneously cleaned up after failed installation of
an action handler in tpmm_chip_alloc() (pointed out by Jarkko Sakkinen)
- make the commit message for patch 1 more detailed
- add fixes tags and kernel logs
Lino Sanfilippo (1):
tpm: fix reference counting for struct tpm_chip
drivers/char/tpm/tpm-chip.c | 80 ++++++++++++++++++++++++++++-----------------
1 file changed, 50 insertions(+), 30 deletions(-)
--
2.7.4
From: Lino Sanfilippo <[email protected]>
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 implemenation 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.
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 <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>
Signed-off-by: Lino Sanfilippo <[email protected]>
Cc: [email protected]
---
drivers/char/tpm/tpm-chip.c | 80 ++++++++++++++++++++++++++++-----------------
1 file changed, 50 insertions(+), 30 deletions(-)
diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index ddaeceb..44cac3a 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -344,7 +344,6 @@ 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 +351,20 @@ 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 +376,6 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev,
return chip;
out:
- put_device(&chip->devs);
put_device(&chip->dev);
return ERR_PTR(rc);
}
@@ -431,6 +410,46 @@ struct tpm_chip *tpmm_chip_alloc(struct device *pdev,
}
EXPORT_SYMBOL_GPL(tpmm_chip_alloc);
+static int tpm_add_tpm2_char_device(struct tpm_chip *chip)
+{
+ int rc;
+
+ device_initialize(&chip->devs);
+ chip->devs.parent = chip->dev.parent;
+ chip->devs.class = tpmrm_class;
+
+ rc = dev_set_name(&chip->devs, "tpmrm%d", chip->dev_num);
+ if (rc)
+ goto out_put_devs;
+ /*
+ * 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 = 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_put_devs;
+ }
+
+ return 0;
+
+out_put_devs:
+ put_device(&chip->devs);
+
+ return rc;
+}
+
static int tpm_add_char_device(struct tpm_chip *chip)
{
int rc;
@@ -445,14 +464,9 @@ 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_add_tpm2_char_device(chip);
+ if (rc)
+ goto del_cdev;
}
/* Make the chip available. */
@@ -460,6 +474,10 @@ 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;
+
+del_cdev:
+ cdev_device_del(&chip->cdev, &chip->dev);
return rc;
}
@@ -640,8 +658,10 @@ 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);
--
2.7.4
On Tue, Feb 16, 2021 at 01:31:00AM +0100, Lino Sanfilippo wrote:
> From: Lino Sanfilippo <[email protected]>
>
> The following sequence of operations results in a refcount warning:
>
> 1. Open device /dev/tpmrm
Add '.' to end.
> 2. Remove module tpm_tis_spi
Add '.' to end.
> 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 implemenation 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.
>
> 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 <[email protected]>
> Signed-off-by: Jason Gunthorpe <[email protected]>
> Signed-off-by: Lino Sanfilippo <[email protected]>
> Cc: [email protected]
Put Cc first.
> ---
> drivers/char/tpm/tpm-chip.c | 80 ++++++++++++++++++++++++++++-----------------
> 1 file changed, 50 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> index ddaeceb..44cac3a 100644
> --- a/drivers/char/tpm/tpm-chip.c
> +++ b/drivers/char/tpm/tpm-chip.c
> @@ -344,7 +344,6 @@ 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 +351,20 @@ 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 +376,6 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev,
> return chip;
>
> out:
> - put_device(&chip->devs);
> put_device(&chip->dev);
> return ERR_PTR(rc);
> }
> @@ -431,6 +410,46 @@ struct tpm_chip *tpmm_chip_alloc(struct device *pdev,
> }
> EXPORT_SYMBOL_GPL(tpmm_chip_alloc);
>
> +static int tpm_add_tpm2_char_device(struct tpm_chip *chip)
> +{
> + int rc;
> +
> + device_initialize(&chip->devs);
> + chip->devs.parent = chip->dev.parent;
> + chip->devs.class = tpmrm_class;
> +
> + rc = dev_set_name(&chip->devs, "tpmrm%d", chip->dev_num);
> + if (rc)
> + goto out_put_devs;
> + /*
> + * 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 = 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_put_devs;
> + }
> +
> + return 0;
> +
> +out_put_devs:
> + put_device(&chip->devs);
> +
> + return rc;
> +}
> +
> static int tpm_add_char_device(struct tpm_chip *chip)
> {
> int rc;
> @@ -445,14 +464,9 @@ 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_add_tpm2_char_device(chip);
> + if (rc)
> + goto del_cdev;
> }
>
> /* Make the chip available. */
> @@ -460,6 +474,10 @@ 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;
> +
> +del_cdev:
> + cdev_device_del(&chip->cdev, &chip->dev);
> return rc;
> }
>
> @@ -640,8 +658,10 @@ 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);
> --
> 2.7.4
>
Other than that, this looks good to me.
If this passes testing, I can fix those nit's.
I'll test this post 5.12 PR.
/Jarkko
On Tue, Feb 16, 2021 at 01:31:00AM +0100, Lino Sanfilippo wrote:
>
> +static int tpm_add_tpm2_char_device(struct tpm_chip *chip)
> +{
> + int rc;
> +
> + device_initialize(&chip->devs);
> + chip->devs.parent = chip->dev.parent;
> + chip->devs.class = tpmrm_class;
> +
> + rc = dev_set_name(&chip->devs, "tpmrm%d", chip->dev_num);
> + if (rc)
> + goto out_put_devs;
> + /*
> + * 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 = 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_put_devs;
> + }
> +
> + return 0;
> +
> +out_put_devs:
> + put_device(&chip->devs);
I'd rather you organize this so chip->devs.release and the get_device
is always sent instead of having the possiblity for a put_device that
doesn't call release
Jason
On Tue, Feb 16, 2021 at 08:53:42AM -0400, Jason Gunthorpe wrote:
> On Tue, Feb 16, 2021 at 01:31:00AM +0100, Lino Sanfilippo wrote:
> >
> > +static int tpm_add_tpm2_char_device(struct tpm_chip *chip)
BTW, this naming is crap.
- 2x tpm
- char is useless
-> tpm2_add_device
> > +{
> > + int rc;
> > +
> > + device_initialize(&chip->devs);
> > + chip->devs.parent = chip->dev.parent;
> > + chip->devs.class = tpmrm_class;
> > +
> > + rc = dev_set_name(&chip->devs, "tpmrm%d", chip->dev_num);
> > + if (rc)
> > + goto out_put_devs;
Right, and empty line missing here.
> > + /*
> > + * 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);
Isn't this less than 100 chars?
> > + cdev_init(&chip->cdevs, &tpmrm_fops);
> > + chip->cdevs.owner = THIS_MODULE;
> > +
> > + 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_put_devs;
> > + }
> > +
> > + return 0;
> > +
> > +out_put_devs:
> > + put_device(&chip->devs);
>
> I'd rather you organize this so chip->devs.release and the get_device
> is always sent instead of having the possiblity for a put_device that
> doesn't call release
/Jarkko
On Tue, Feb 16, 2021 at 06:04:42PM +0200, Jarkko Sakkinen wrote:
> On Tue, Feb 16, 2021 at 08:53:42AM -0400, Jason Gunthorpe wrote:
> > On Tue, Feb 16, 2021 at 01:31:00AM +0100, Lino Sanfilippo wrote:
> > >
> > > +static int tpm_add_tpm2_char_device(struct tpm_chip *chip)
>
> BTW, this naming is crap.
>
> - 2x tpm
> - char is useless
>
> -> tpm2_add_device
Actually, tpm2s_add_device() add put it to tpm2-space.c.
> > > +{
> > > + int rc;
> > > +
> > > + device_initialize(&chip->devs);
> > > + chip->devs.parent = chip->dev.parent;
> > > + chip->devs.class = tpmrm_class;
> > > +
> > > + rc = dev_set_name(&chip->devs, "tpmrm%d", chip->dev_num);
> > > + if (rc)
> > > + goto out_put_devs;
>
> Right, and empty line missing here.
>
> > > + /*
> > > + * 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);
>
> Isn't this less than 100 chars?
>
> > > + cdev_init(&chip->cdevs, &tpmrm_fops);
> > > + chip->cdevs.owner = THIS_MODULE;
> > > +
> > > + 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_put_devs;
> > > + }
> > > +
> > > + return 0;
> > > +
> > > +out_put_devs:
> > > + put_device(&chip->devs);
> >
> > I'd rather you organize this so chip->devs.release and the get_device
> > is always sent instead of having the possiblity for a put_device that
> > doesn't call release
>
> /Jarkko
On Tue, Feb 16, 2021 at 06:09:50PM +0200, Jarkko Sakkinen wrote:
> On Tue, Feb 16, 2021 at 06:04:42PM +0200, Jarkko Sakkinen wrote:
> > On Tue, Feb 16, 2021 at 08:53:42AM -0400, Jason Gunthorpe wrote:
> > > On Tue, Feb 16, 2021 at 01:31:00AM +0100, Lino Sanfilippo wrote:
> > > >
> > > > +static int tpm_add_tpm2_char_device(struct tpm_chip *chip)
> >
> > BTW, this naming is crap.
> >
> > - 2x tpm
> > - char is useless
> >
> > -> tpm2_add_device
>
> Actually, tpm2s_add_device() add put it to tpm2-space.c.
No, tpms_add_device() :-)
(sorry)
/Jarkko
>
> > > > +{
> > > > + int rc;
> > > > +
> > > > + device_initialize(&chip->devs);
> > > > + chip->devs.parent = chip->dev.parent;
> > > > + chip->devs.class = tpmrm_class;
> > > > +
> > > > + rc = dev_set_name(&chip->devs, "tpmrm%d", chip->dev_num);
> > > > + if (rc)
> > > > + goto out_put_devs;
> >
> > Right, and empty line missing here.
> >
> > > > + /*
> > > > + * 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);
> >
> > Isn't this less than 100 chars?
> >
> > > > + cdev_init(&chip->cdevs, &tpmrm_fops);
> > > > + chip->cdevs.owner = THIS_MODULE;
> > > > +
> > > > + 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_put_devs;
> > > > + }
> > > > +
> > > > + return 0;
> > > > +
> > > > +out_put_devs:
> > > > + put_device(&chip->devs);
> > >
> > > I'd rather you organize this so chip->devs.release and the get_device
> > > is always sent instead of having the possiblity for a put_device that
> > > doesn't call release
> >
> > /Jarkko
...
> > > + get_device(&chip->dev);
> > > + chip->devs.release = tpm_devs_release;
> > > + chip->devs.devt =
> > > + MKDEV(MAJOR(tpm_devt), chip->dev_num + TPM_NUM_DEVICES);
>
> Isn't this less than 100 chars?
Still best kept under 80 if 'reasonable'?
Really it is just split in the wrong place:
chip->devs.devt = MKDEV(MAJOR(tpm_devt),
chip->dev_num + TPM_NUM_DEVICES);
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
On 2/15/21 7:31 PM, Lino Sanfilippo wrote:
> From: Lino Sanfilippo <[email protected]>
>
> 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 implemenation 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.
>
> 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 <[email protected]>
> Signed-off-by: Jason Gunthorpe <[email protected]>
> Signed-off-by: Lino Sanfilippo <[email protected]>
> Cc: [email protected]
I know you'll post another version, but anyway:
Tested-by: Stefan Berger <[email protected]>
Hi,
On 16.02.21 at 13:53, Jason Gunthorpe wrote:
> On Tue, Feb 16, 2021 at 01:31:00AM +0100, Lino Sanfilippo wrote:
>>
>> +static int tpm_add_tpm2_char_device(struct tpm_chip *chip)
>> +{
>> + int rc;
>> +
>> + device_initialize(&chip->devs);
>> + chip->devs.parent = chip->dev.parent;
>> + chip->devs.class = tpmrm_class;
>> +
>> + rc = dev_set_name(&chip->devs, "tpmrm%d", chip->dev_num);
>> + if (rc)
>> + goto out_put_devs;
>> + /*
>> + * 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 = 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_put_devs;
>> + }
>> +
>> + return 0;
>> +
>> +out_put_devs:
>> + put_device(&chip->devs);
>
> I'd rather you organize this so chip->devs.release and the get_device
> is always sent instead of having the possiblity for a put_device that
> doesn't call release
>
Agreed, I will change it. It should not make a difference in terms of correctness
but I see that it is less confusing if both error cases are handled similarly (plus its
only a minimal change).
Best regards,
Lino
Hi,
On 16.02.21 at 17:11, Jarkko Sakkinen wrote:
> On Tue, Feb 16, 2021 at 06:09:50PM +0200, Jarkko Sakkinen wrote:
>> On Tue, Feb 16, 2021 at 06:04:42PM +0200, Jarkko Sakkinen wrote:
>>> On Tue, Feb 16, 2021 at 08:53:42AM -0400, Jason Gunthorpe wrote:
>>>> On Tue, Feb 16, 2021 at 01:31:00AM +0100, Lino Sanfilippo wrote:
>>>>>
>>>>> +static int tpm_add_tpm2_char_device(struct tpm_chip *chip)
>>>
>>> BTW, this naming is crap.
>>>
>>> - 2x tpm
>>> - char is useless
>>>
>>> -> tpm2_add_device
>>
>> Actually, tpm2s_add_device() add put it to tpm2-space.c.
>
> No, tpms_add_device() :-)
>
> (sorry)
>
> /Jarkko
>
I strongly assume you mean tmp2_add_device() :) I will move and rename the function
accordingly.
Thanks,
Lino
Hi
On 16.02.21 at 17:04, Jarkko Sakkinen wrote:
>>> + /*
>>> + * 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);
>
> Isn't this less than 100 chars?
>
I just chose the same formatting that the original code used. Personally I prefer what
David suggested, so if there is no objection against it I will format it this way.
Regards,
Lino
Hi Stefan,
On 16.02.21 at 17:52, Stefan Berger wrote:
> On 2/15/21 7:31 PM, Lino Sanfilippo wrote:
>> From: Lino Sanfilippo <[email protected]>
>>
>> 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 implemenation 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.
>>
>> 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 <[email protected]>
>> Signed-off-by: Jason Gunthorpe <[email protected]>
>> Signed-off-by: Lino Sanfilippo <[email protected]>
>> Cc: [email protected]
>
>
> I know you'll post another version, but anyway:
>
> Tested-by: Stefan Berger <[email protected]>
Thank you for testing this, I will send a v5 shortly.
Regards,
Lino
On Tue, Feb 16, 2021 at 04:31:26PM +0000, David Laight wrote:
> ...
> > > > + get_device(&chip->dev);
> > > > + chip->devs.release = tpm_devs_release;
> > > > + chip->devs.devt =
> > > > + MKDEV(MAJOR(tpm_devt), chip->dev_num + TPM_NUM_DEVICES);
> >
> > Isn't this less than 100 chars?
>
> Still best kept under 80 if 'reasonable'?
>
> Really it is just split in the wrong place:
> chip->devs.devt = MKDEV(MAJOR(tpm_devt),
> chip->dev_num + TPM_NUM_DEVICES);
Well it looks crap IMHO. Would be more reasonable to have it in a single
like. And it is legit too, since it is accepted by checkpatch.
You might break the lines within 80 chars if it is somehow "logically"
consistent.
>
> David
>
> -
> Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
> Registration No: 1397386 (Wales)
>
>
/Jarkko
On Thu, Feb 18, 2021 at 12:14:11AM +0200, Jarkko Sakkinen wrote:
> On Tue, Feb 16, 2021 at 04:31:26PM +0000, David Laight wrote:
> > ...
> > > > > + get_device(&chip->dev);
> > > > > + chip->devs.release = tpm_devs_release;
> > > > > + chip->devs.devt =
> > > > > + MKDEV(MAJOR(tpm_devt), chip->dev_num + TPM_NUM_DEVICES);
> > >
> > > Isn't this less than 100 chars?
> >
> > Still best kept under 80 if 'reasonable'?
> >
> > Really it is just split in the wrong place:
> > chip->devs.devt = MKDEV(MAJOR(tpm_devt),
> > chip->dev_num + TPM_NUM_DEVICES);
>
>
> Well it looks crap IMHO. Would be more reasonable to have it in a single
> like. And it is legit too, since it is accepted by checkpatch.
>
> You might break the lines within 80 chars if it is somehow "logically"
> consistent.
FWIW, I've become kind of tired of the style wishywashyness I've
mostly been happy to accept anything that clang-format spits out for
ordinary C constructs.
It is good enough and universally usable. If devs don't have it linked
to their editor to format single expression or format selected blocks,
they are missing out :)
The community consensus on style is quite unclear. Is 1 or 2 above the
majority preference? Does this case fall under the new "use more than
80 cols if it improves readability?" I have no idea.
Frankly, for most people writing driver code, if they consistently use
clang-format their work will be alot better than if they try to do it
by hand. It takes a lot of experiance to reliably eyeball something
close to the kernel style..
Jason
On Wed, Feb 17, 2021 at 09:27:02PM -0400, Jason Gunthorpe wrote:
> On Thu, Feb 18, 2021 at 12:14:11AM +0200, Jarkko Sakkinen wrote:
> > On Tue, Feb 16, 2021 at 04:31:26PM +0000, David Laight wrote:
> > > ...
> > > > > > + get_device(&chip->dev);
> > > > > > + chip->devs.release = tpm_devs_release;
> > > > > > + chip->devs.devt =
> > > > > > + MKDEV(MAJOR(tpm_devt), chip->dev_num + TPM_NUM_DEVICES);
> > > >
> > > > Isn't this less than 100 chars?
> > >
> > > Still best kept under 80 if 'reasonable'?
> > >
> > > Really it is just split in the wrong place:
> > > chip->devs.devt = MKDEV(MAJOR(tpm_devt),
> > > chip->dev_num + TPM_NUM_DEVICES);
> >
> >
> > Well it looks crap IMHO. Would be more reasonable to have it in a single
> > like. And it is legit too, since it is accepted by checkpatch.
> >
> > You might break the lines within 80 chars if it is somehow "logically"
> > consistent.
>
> FWIW, I've become kind of tired of the style wishywashyness I've
> mostly been happy to accept anything that clang-format spits out for
> ordinary C constructs.
A. I would not mind if it was already merged. Since it isn't, I don't
see the point not fixing it.
> It is good enough and universally usable. If devs don't have it linked
> to their editor to format single expression or format selected blocks,
> they are missing out :)
>
> The community consensus on style is quite unclear. Is 1 or 2 above the
> majority preference? Does this case fall under the new "use more than
> 80 cols if it improves readability?" I have no idea.
B. I need to maintain this, once it's merged.
C. A smaller diff for a critical bug fix. I actually allow style
compromises for fixes to be backported *when* it makes the overall
diff smaller.
D. Has more odds to make future changes smaller as the whole thing is
in a single code line.
> Frankly, for most people writing driver code, if they consistently use
> clang-format their work will be alot better than if they try to do it
> by hand. It takes a lot of experiance to reliably eyeball something
> close to the kernel style..
For me it gives a framework to review patches in multiple subsystems.
If I have to constantly think whether to allow this and that shift
from the kernel coding style, it makes the whole process for me more
fuzzy and chaotic.
As I said (A), it would not be end of the world if this had been
merged already. I also want to state that I do sometimes make mistakes
when reviewing code, and am happy to take critique from that :-)
> Jason
/Jarkko