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authorJosh Zimmerman <joshz@google.com>2017-06-25 23:53:24 +0200
committerJames Morris <james.l.morris@oracle.com>2017-07-07 01:49:24 +0200
commitd1bd4a792d3961a04e6154118816b00167aad91a (patch)
treef43ed322b34945692400b32841b4fae80b97d3a8 /drivers/char/tpm/tpm-sysfs.c
parentAdd "shutdown" to "struct class". (diff)
downloadlinux-d1bd4a792d3961a04e6154118816b00167aad91a.tar.xz
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tpm: Issue a TPM2_Shutdown for TPM2 devices.
If a TPM2 loses power without a TPM2_Shutdown command being issued (a "disorderly reboot"), it may lose some state that has yet to be persisted to NVRam, and will increment the DA counter. After the DA counter gets sufficiently large, the TPM will lock the user out. NOTE: This only changes behavior on TPM2 devices. Since TPM1 uses sysfs, and sysfs relies on implicit locking on chip->ops, it is not safe to allow this code to run in TPM1, or to add sysfs support to TPM2, until that locking is made explicit. Signed-off-by: Josh Zimmerman <joshz@google.com> Cc: stable@vger.kernel.org Fixes: 74d6b3ceaa17 ("tpm: fix suspend/resume paths for TPM 2.0") Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Signed-off-by: James Morris <james.l.morris@oracle.com>
Diffstat (limited to '')
-rw-r--r--drivers/char/tpm/tpm-sysfs.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
index 4bd0997cfa2d..938d03ce30fe 100644
--- a/drivers/char/tpm/tpm-sysfs.c
+++ b/drivers/char/tpm/tpm-sysfs.c
@@ -294,6 +294,9 @@ static const struct attribute_group tpm_dev_group = {
void tpm_sysfs_add_device(struct tpm_chip *chip)
{
+ /* XXX: If you wish to remove this restriction, you must first update
+ * tpm_sysfs to explicitly lock chip->ops.
+ */
if (chip->flags & TPM_CHIP_FLAG_TPM2)
return;