From e0d9d21958cbd811e9b590123e2c4540fb4111f2 Mon Sep 17 00:00:00 2001
From: Eugene Wissner <belka@caraus.de>
Date: Mon, 30 Jul 2018 16:16:59 +0200
Subject: [PATCH] Fix issue 19128 - argument to alloca may be too large

---
 src/rt/arrayassign.d | 35 +++++++++++++++++++++++++++++++----
 1 file changed, 31 insertions(+), 4 deletions(-)

diff --git a/src/rt/arrayassign.d b/src/rt/arrayassign.d
index c633d9b3d6..6277af78f0 100644
--- a/src/rt/arrayassign.d
+++ b/src/rt/arrayassign.d
@@ -30,8 +30,25 @@ extern (C) void[] _d_arrayassign(TypeInfo ti, void[] from, void[] to)
 
     // Need a temporary buffer tmp[] big enough to hold one element
     void[16] buf = void;
-    void* ptmp = (elementSize > buf.sizeof) ? alloca(elementSize) : buf.ptr;
-    return _d_arrayassign_l(ti, from, to, ptmp);
+    void* ptmp;
+    if (elementSize <= buf.sizeof)
+    {
+        ptmp = buf.ptr;
+    }
+    else if (elementSize < 1024)
+    {
+        ptmp = alloca(elementSize);
+    }
+    else
+    {
+        ptmp = malloc(elementSize);
+    }
+    auto dst = _d_arrayassign_l(ti, from, to, ptmp);
+    if (elementSize >= 1024)
+    {
+        free(ptmp);
+    }
+    return dst;
 }
 
 /**
@@ -209,12 +226,18 @@ extern (C) void* _d_arraysetassign(void* p, void* value, int count, TypeInfo ti)
     //Need a temporary buffer tmp[] big enough to hold one element
     void[16] buf = void;
     void[] tmp;
-    if (element_size > buf.sizeof)
+    if (element_size <= buf.sizeof)
+    {
+        tmp = buf[];
+    }
+    else if (element_size < 1024)
     {
         tmp = alloca(element_size)[0 .. element_size];
     }
     else
-        tmp = buf[];
+    {
+        tmp = malloc(element_size)[0 .. element_size];
+    }
 
     foreach (i; 0 .. count)
     {
@@ -224,6 +247,10 @@ extern (C) void* _d_arraysetassign(void* p, void* value, int count, TypeInfo ti)
         ti.destroy(tmp.ptr);
         p += element_size;
     }
+    if (element_size >= 1024)
+    {
+        free(tmp.ptr);
+    }
     return pstart;
 }