tpm: fix reading of permanent flags

The offset of the permanent flags structure is in a different
place in the response compared to what the code is doing,
which gives us a completely useless result.

Fix by replacing hand-crafted code with generic parser
infrastructure.

Signed-off-by: André Draszik <adraszik@tycoint.com>
Acked-by: Simon Glass <sjg@chromium.org>

diff --git a/lib/tpm.c b/lib/tpm.c
index d1cf5a8a1679fa7ab7f828c8b4290bb8aca80fe0..5659fa5e18beea1a028647c97b6e143f065840be 100644 (file)
--- a/lib/tpm.c
+++ b/lib/tpm.c
@@ -607,14 +607,24 @@ uint32_t tpm_get_permanent_flags(struct tpm_permanent_flags *pflags)
                0x0, 0x0, 0x0, 0x4,     /* subcap size */
                0x0, 0x0, 0x1, 0x8,     /* subcap value */
        };
+       const size_t data_size_offset = TPM_HEADER_SIZE;
+       const size_t data_offset = TPM_HEADER_SIZE + sizeof (uint32_t);
        uint8_t response[COMMAND_BUFFER_SIZE];
        size_t response_length = sizeof(response);
        uint32_t err;
+       uint32_t data_size;
 
        err = tpm_sendrecv_command(command, response, &response_length);
        if (err)
                return err;
-       memcpy(pflags, response + TPM_HEADER_SIZE, sizeof(*pflags));
+       if (unpack_byte_string(response, response_length, "d",
+                              data_size_offset, &data_size))
+               return TPM_LIB_ERROR;
+       if (data_size < sizeof(*pflags))
+               return TPM_LIB_ERROR;
+       if (unpack_byte_string(response, response_length, "s",
+                              data_offset, pflags, sizeof(*pflags)))
+               return TPM_LIB_ERROR;
 
        return 0;
 }