Limit the file hash algorithm name length

Instead of assuming the file hash algorithm is a properly NULL terminated
string, properly limit the "algo:<hash>" field size.

Reviewed-by: Petr Vorel <pvorel@suse.cz>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

src/evmctl.c

@@ -1603,7 +1603,7 @@ void ima_ng_show(struct template_entry *entry)
 	total_len -= sizeof(field_len);
 
 	algo = (char *)fieldp;
-	len = strlen(algo) + 1;
+	len = strnlen(algo, field_len - 1) + 1;
 	digest_len = field_len - len;
 	digest = fieldp + len;