From: Nirbheek Chauhan <nirbheek.chauhan@gmail.com>
Date: Wed, 8 Jul 2020 17:40:34 +0000 (+0530)
Subject: crypto/win: Don't use disallowed APIs on UWP
X-Git-Tag: openssl-3.0.0-alpha10~10
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=ce1119265005bd254fc92395f72490c19adc707c;p=thirdparty%2Fopenssl.git

crypto/win: Don't use disallowed APIs on UWP

CreateFiber and ConvertThreadToFiber are not allowed in Windows Store
(Universal Windows Platform) apps since they have been replaced by
their Ex variants which have a new dwFlags parameter.

This flag allows the fiber to do floating-point arithmetic in the
fiber on x86, which would silently cause corruption otherwise since
the floating-point state is not switched by default.

Switch to these "new" APIs which were added in Vista.

See: https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-createfiberex#parameters

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/12400)
---

diff --git a/crypto/async/arch/async_win.c b/crypto/async/arch/async_win.c
index 0db9efe3c1c..72cc27c214c 100644
--- a/crypto/async/arch/async_win.c
+++ b/crypto/async/arch/async_win.c
@@ -34,7 +34,11 @@ void async_local_cleanup(void)
 
 int async_fibre_init_dispatcher(async_fibre *fibre)
 {
+# if defined(_WIN32_WINNT) && _WIN32_WINNT >= 0x600
+    fibre->fibre = ConvertThreadToFiberEx(NULL, FIBER_FLAG_FLOAT_SWITCH);
+# else
     fibre->fibre = ConvertThreadToFiber(NULL);
+# endif
     if (fibre->fibre == NULL) {
         fibre->converted = 0;
         fibre->fibre = GetCurrentFiber();
diff --git a/crypto/async/arch/async_win.h b/crypto/async/arch/async_win.h
index 87e661d7663..eb61b032e0c 100644
--- a/crypto/async/arch/async_win.h
+++ b/crypto/async/arch/async_win.h
@@ -26,8 +26,16 @@ typedef struct async_fibre_st {
 
 # define async_fibre_swapcontext(o,n,r) \
         (SwitchToFiber((n)->fibre), 1)
-# define async_fibre_makecontext(c) \
+
+# if defined(_WIN32_WINNT) && _WIN32_WINNT >= 0x600
+#   define async_fibre_makecontext(c) \
+        ((c)->fibre = CreateFiberEx(0, 0, FIBER_FLAG_FLOAT_SWITCH, \
+                                    async_start_func_win, 0))
+# else
+#   define async_fibre_makecontext(c) \
         ((c)->fibre = CreateFiber(0, async_start_func_win, 0))
+# endif
+
 # define async_fibre_free(f)             (DeleteFiber((f)->fibre))
 
 int async_fibre_init_dispatcher(async_fibre *fibre);