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

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 <[email protected]>
Acked-by: Mimi Zohar <[email protected]>
Reviewed-by: Jarkko Sakkinen <[email protected]>
Signed-off-by: Jarkko Sakkinen <[email protected]>

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 6e368ee7bbecefd6f068fbe4cd6fb06a258c3068..bd2128e0b56cc8c4774acdd2adec682847d911f0 100644 (file)
--- 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),