From: Matt Caswell <matt@openssl.org>
Date: Mon, 14 Nov 2016 12:00:45 +0000 (+0000)
Subject: Revert "Fixed deadlock in CRYPTO_THREAD_run_once for Windows"
X-Git-Tag: OpenSSL_1_1_0d~146
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=c028052c4cfc39dc99f735f1743b18867547129f;p=openssl

Revert "Fixed deadlock in CRYPTO_THREAD_run_once for Windows"

This reverts commit edc18749bd5dfb7e12513d3978f78f9b56104fd6.

The proposed fix is incorrect. It marks the "run_once" code as having
finished before it has. The intended semantics of run_once is that no
threads should proceed until the code has run exactly once. With this
change the "second" thread will think the run_once code has already been
run and will continue, even though it is still in progress. This could
result in a crash or other incorrect behaviour.

Reviewed-by: Tim Hudson <tjh@openssl.org>
---

diff --git a/crypto/threads_win.c b/crypto/threads_win.c
index 5347c9e46b..4e0de908ee 100644
--- a/crypto/threads_win.c
+++ b/crypto/threads_win.c
@@ -78,8 +78,8 @@ int CRYPTO_THREAD_run_once(CRYPTO_ONCE *once, void (*init)(void))
     do {
         result = InterlockedCompareExchange(lock, ONCE_ININIT, ONCE_UNINITED);
         if (result == ONCE_UNINITED) {
-            *lock = ONCE_DONE;
             init();
+            *lock = ONCE_DONE;
             return 1;
         }
     } while (result == ONCE_ININIT);