svn commit: r345842 - head/sys/dev/tpm

Marcin Wojtas mw at FreeBSD.org
Wed Apr 3 08:22:59 UTC 2019


Author: mw
Date: Wed Apr  3 08:22:58 2019
New Revision: 345842
URL: https://svnweb.freebsd.org/changeset/base/345842

Log:
  Add a cv_wait to the TPM2.0 harvesting function
  
  Harvesting has to compete for the TPM chip with userspace.
  Before this change the callout could hijack an unread buffer
  causing a userspace call to the TPM to fail.
  
  Submitted by: Kornel Duleba <mindal at semihalf.com>
  Reviewed by: delphij
  Obtained from: Semihalf
  Sponsored by: Stormshield
  Differential Revision: https://reviews.freebsd.org/D19712

Modified:
  head/sys/dev/tpm/tpm20.c

Modified: head/sys/dev/tpm/tpm20.c
==============================================================================
--- head/sys/dev/tpm/tpm20.c	Wed Apr  3 08:18:18 2019	(r345841)
+++ head/sys/dev/tpm/tpm20.c	Wed Apr  3 08:22:58 2019	(r345842)
@@ -263,6 +263,8 @@ tpm20_harvest(void *arg)
 
 	sc = arg;
 	sx_xlock(&sc->dev_lock);
+	while (sc->pending_data_length != 0)
+		cv_wait(&sc->buf_cv, &sc->dev_lock);
 
 	memcpy(sc->buf, cmd, sizeof(cmd));
 	result = sc->transmit(sc, sizeof(cmd));


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