mbedtls_timing_get_timer: don't use uninitialized memory
mbedtls_timing_get_timer with reset=1 is called both to initialize a
timer object and to reset an already-initialized object. In an
initial call, the content of the data structure is indeterminate, so
the code should not read from it. This could crash if signed overflows
trap, for example.
As a consequence, on reset, we can't return the previously elapsed
time as was previously done on Windows. Return 0 as was done on Unix.
diff --git a/ChangeLog b/ChangeLog
index bfba279..2061be0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -10,6 +10,7 @@
Found by projectgus and jethrogb, #836.
* Fix usage help in ssl_server2 example. Found and fixed by Bei Lin.
* Fix mbedtls_timing_alarm(0) on Unix.
+ * Fix use of uninitialized memory in mbedtls_timing_get_timer when reset=1.
= mbed TLS 2.6.0 branch released 2017-08-10