[PATCH] tpm: Fix expected number of response bytes of TPM1.2 PCR Extend

[Stefan Berger]

The TPM1.2 PCR Extend operation only returns 20 bytes in the body,
which is the size of the PCR state.

This fixes a problem where IMA gets errors with every PCR Extend.

Fixes: c659af78eb7b ("tpm: Check size of response before accessing data")
Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxxxxxxx>
Acked-by: Mimi Zohar <zohar@xxxxxxxxxx>
---
 drivers/char/tpm/tpm-interface.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 6e368ee..bd2128e 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -767,7 +767,7 @@ EXPORT_SYMBOL_GPL(tpm_pcr_read);
 
 #define TPM_ORD_PCR_EXTEND cpu_to_be32(20)
 #define EXTEND_PCR_RESULT_SIZE 34
-#define EXTEND_PCR_RESULT_BODY_SIZE 24
+#define EXTEND_PCR_RESULT_BODY_SIZE 20
 static const struct tpm_input_header pcrextend_header = {
 	.tag = TPM_TAG_RQU_COMMAND,
 	.length = cpu_to_be32(34),
-- 
2.4.3