Message ID | 1612482643-11796-2-git-send-email-LinoSanfilippo@gmx.de |
---|---|
State | New |
Headers | show |
Series | TPM fixes | expand |
On Fri, Feb 05, 2021 at 12:50:42AM +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 removing the flag condition. > > 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 also by installing an action handler that puts chip->devs as soon > as the chip is unregistered. > > Fixes: fdc915f7f719 ("tpm: expose spaces via a device link /dev/tpmrm<n>") > Fixes: 8979b02aaf1d ("tpm: Fix reference count to main device") > Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com> > --- > drivers/char/tpm/tpm-chip.c | 18 +++++++++++++++--- > drivers/char/tpm/tpm_ftpm_tee.c | 2 ++ > drivers/char/tpm/tpm_vtpm_proxy.c | 1 + > 3 files changed, 18 insertions(+), 3 deletions(-) <formletter> This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read: https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html for how to do this properly. </formletter>
diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c index ddaeceb..3ace199 100644 --- a/drivers/char/tpm/tpm-chip.c +++ b/drivers/char/tpm/tpm-chip.c @@ -360,8 +360,7 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev, * 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); + get_device(&chip->dev); if (chip->dev_num == 0) chip->dev.devt = MKDEV(MISC_MAJOR, TPM_MINOR); @@ -422,8 +421,21 @@ struct tpm_chip *tpmm_chip_alloc(struct device *pdev, rc = devm_add_action_or_reset(pdev, (void (*)(void *)) put_device, &chip->dev); - if (rc) + if (rc) { + put_device(&chip->devs); return ERR_PTR(rc); + } + + rc = devm_add_action_or_reset(pdev, + (void (*)(void *)) put_device, + &chip->devs); + if (rc) { + devm_remove_action(pdev, + (void (*)(void *)) put_device, + &chip->dev); + put_device(&chip->dev); + return ERR_PTR(rc); + } dev_set_drvdata(pdev, chip); diff --git a/drivers/char/tpm/tpm_ftpm_tee.c b/drivers/char/tpm/tpm_ftpm_tee.c index 2ccdf8a..82858c2 100644 --- a/drivers/char/tpm/tpm_ftpm_tee.c +++ b/drivers/char/tpm/tpm_ftpm_tee.c @@ -286,6 +286,7 @@ static int ftpm_tee_probe(struct device *dev) out_chip: put_device(&pvt_data->chip->dev); + put_device(&pvt_data->chip->devs); out_chip_alloc: tee_shm_free(pvt_data->shm); out_shm_alloc: @@ -318,6 +319,7 @@ static int ftpm_tee_remove(struct device *dev) tpm_chip_unregister(pvt_data->chip); /* frees chip */ + put_device(&pvt_data->chip->devs); put_device(&pvt_data->chip->dev); /* Free the shared memory pool */ diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c b/drivers/char/tpm/tpm_vtpm_proxy.c index 91c772e3..97b60f8 100644 --- a/drivers/char/tpm/tpm_vtpm_proxy.c +++ b/drivers/char/tpm/tpm_vtpm_proxy.c @@ -520,6 +520,7 @@ static struct proxy_dev *vtpm_proxy_create_proxy_dev(void) */ static inline void vtpm_proxy_delete_proxy_dev(struct proxy_dev *proxy_dev) { + put_device(&proxy_dev->chip->devs); put_device(&proxy_dev->chip->dev); /* frees chip */ kfree(proxy_dev); }