linux-kernel - Re: [PATCH] tpm_tis: verify locality released before returning from release

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Date:   Mon, 28 May 2018 02:01:47 -0700
From:   Jerry Snitselaar <jsnitsel@...hat.com>
To:     Laurent Bigonville <bigon@...ian.org>
Cc:     linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Peter Huewe <peterhuewe@....de>, Jason Gunthorpe <jgg@...pe.ca>
Subject: Re: [PATCH] tpm_tis: verify locality released before returning from
 release_locality

On Mon May 28 18, Laurent Bigonville wrote:
>Hello,
>
>Top posting, sorry.
>
>I don't know if I did it well to include the "Tested-by" tag because I 
>don't see that the patch has landed in linus branch already.
>
>And as far as I understand, this will not be in the upcoming 4.17 
>release as we are already late in the cycle?
>
>Kind regards,
>
>Laurent Bigonville
>

It should go into his branch during the merge window for 4.18.

>
>Le 11/05/18 à 21:02, Laurent Bigonville a écrit :
>>Le 05/05/18 à 22:03, Jerry Snitselaar a écrit :
>>>On Sat May 05 18, Jerry Snitselaar wrote:
>>>>For certain tpm chips releasing locality can take long enough that a
>>>>subsequent call to request_locality will see the locality as being
>>>>active when the access register is read in check_locality. So check
>>>>that the locality has been released before returning from
>>>>release_locality.
>>>>
>>>>Cc: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
>>>>Cc: Peter Huewe <peterhuewe@....de>
>>>>Cc: Jason Gunthorpe <jgg@...pe.ca>
>>>>Reported-by: Laurent Bigonville <bigon@...ian.org>
>>>>Signed-off-by: Jerry Snitselaar <jsnitsel@...hat.com>
>>Tested-by: Laurent Bigonville <bigon@...ian.org>
>>>>---
>>>>drivers/char/tpm/tpm_tis_core.c | 47 
>>>>++++++++++++++++++++++++++++++++++++++++-
>>>>1 file changed, 46 insertions(+), 1 deletion(-)
>>>>
>>>>diff --git a/drivers/char/tpm/tpm_tis_core.c 
>>>>b/drivers/char/tpm/tpm_tis_core.c
>>>>index 5a1f47b43947..d547cd309dbd 100644
>>>>--- a/drivers/char/tpm/tpm_tis_core.c
>>>>+++ b/drivers/char/tpm/tpm_tis_core.c
>>>>@@ -143,13 +143,58 @@ static bool check_locality(struct tpm_chip 
>>>>*chip, int l)
>>>>    return false;
>>>>}
>>>>
>>>>+static bool locality_inactive(struct tpm_chip *chip, int l)
>>>>+{
>>>>+    struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
>>>>+    int rc;
>>>>+    u8 access;
>>>>+
>>>>+    rc = tpm_tis_read8(priv, TPM_ACCESS(l), &access);
>>>>+    if (rc < 0)
>>>>+        return false;
>>>>+
>>>>+    if ((access & (TPM_ACCESS_VALID | TPM_ACCESS_ACTIVE_LOCALITY))
>>>>+        == TPM_ACCESS_VALID)
>>>>+        return true;
>>>>+
>>>>+    return false;
>>>>+}
>>>>+
>>>>static int release_locality(struct tpm_chip *chip, int l)
>>>>{
>>>>    struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
>>>>+    unsigned long stop, timeout;
>>>>+    long rc;
>>>>
>>>>    tpm_tis_write8(priv, TPM_ACCESS(l), TPM_ACCESS_ACTIVE_LOCALITY);
>>>>
>>>>-    return 0;
>>>>+    stop = jiffies + chip->timeout_a;
>>>>+
>>>>+    if (chip->flags & TPM_CHIP_FLAG_IRQ) {
>>>>+again:
>>>>+        timeout = stop - jiffies;
>>>>+        if ((long)timeout <= 0)
>>>>+            return -1;
>>>>+
>>>>+        rc = wait_event_interruptible_timeout(priv->int_queue,
>>>>+                              (locality_inactive(chip, l)),
>>>>+                              timeout);
>>>>+
>>>>+        if (rc > 0)
>>>>+            return 0;
>>>>+
>>>>+        if (rc == -ERESTARTSYS && freezing(current)) {
>>>>+            clear_thread_flag(TIF_SIGPENDING);
>>>>+            goto again;
>>>>+        }
>>>>+    } else {
>>>>+        do {
>>>>+            if (locality_inactive(chip, l))
>>>>+                return 0;
>>>>+            tpm_msleep(TPM_TIMEOUT);
>>>>+        } while (time_before(jiffies, stop));
>>>>+    }
>>>>+    return -1;
>>>>}
>>>>
>>>>static int request_locality(struct tpm_chip *chip, int l)
>>>>-- 
>>>>2.15.0
>>>>
>>>
>>>Laurent,
>>>
>>>Can you try this patch with your system since it is the one
>>>that has exhibited the problem so far. I've tested on a
>>>tpm2.0 and tpm1.2 system here.
>>>
>>>Regards,
>>>Jerry
>>
>