Re: [PATCH] tpm: vtpm_proxy: Do not access host's event log

[Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>]

On Thu, Nov 17, 2016 at 06:15:20PM -0500, Stefan Berger wrote:

> >>Further, I had the impression that the error unwinding following -ENODEV has
> >>an issue related to sysfs.
> >I don't follow this comment..
> 
> I have encountered this error here, which gets masked when applying the
> previously shown patch.

If tpm_chip_register fails vtpm must not call tpm_chip_unregister:

> [   58.271017]  [<ffffffff8155bd32>] dpm_sysfs_remove+0x22/0x60
> [   58.271017]  [<ffffffff8154e438>] device_del+0x58/0x280
> [   58.271017]  [<ffffffffa024c020>] tpm_chip_unregister+0x40/0xb0 [tpm]
> [   58.271017]  [<ffffffffa0292360>] vtpm_proxy_fops_release+0x40/0x60 [tpm_vtpm_proxy]

So, this is a vtpm thing I missed for 'tpm: Get rid of TPM_CHIP_FLAG_REGISTERED'

Does this do the trick?

diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c b/drivers/char/tpm/tpm_vtpm_proxy.c
index 3d6f6ca81def75..d3a41f9d65c85c 100644
--- a/drivers/char/tpm/tpm_vtpm_proxy.c
+++ b/drivers/char/tpm/tpm_vtpm_proxy.c
@@ -42,6 +42,7 @@ struct proxy_dev {
 	long state;                  /* internal state */
 #define STATE_OPENED_FLAG        BIT(0)
 #define STATE_WAIT_RESPONSE_FLAG BIT(1)  /* waiting for emulator response */
+#define STATE_REGISTERED_FLAG	 BIT(2)
 
 	size_t req_len;              /* length of queued TPM request */
 	size_t resp_len;             /* length of queued TPM response */
@@ -372,6 +373,7 @@ static void vtpm_proxy_work(struct work_struct *work)
 	if (rc)
 		goto err;
 
+	proxy_dev->state |= STATE_REGISTERED_FLAG;
 	return;
 
 err:
@@ -516,7 +518,8 @@ static void vtpm_proxy_delete_device(struct proxy_dev *proxy_dev)
 	 */
 	vtpm_proxy_fops_undo_open(proxy_dev);
 
-	tpm_chip_unregister(proxy_dev->chip);
+	if (proxy_dev->state & STATE_REGISTERED_FLAG)
+		tpm_chip_unregister(proxy_dev->chip);
 
 	vtpm_proxy_delete_proxy_dev(proxy_dev);
 }


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