Avoid endless loop deleting CFGAS_GEFont.

It's a ref-counted class, so if we're in the destructor, the ref
count has hit zero. We can't make a new ref pointer to itself here,
as it will re-invoke the destructor when it goes out of scope. This
should have been an obvious anti-pattern in hindsight.

The object in question can't be in the m_pFontManager, since the font
manager retains a reference, and we wouldn't get to this destructor
while that is present. So the cleanup isn't required.

Fixing this revealed a free-delete mismatch in cxfa_textlayout.cpp.
I also converted to use unique_ptrs in a few places near this issue.

Fixing this revealed a UAF in CFGAS_GEFont, memcpy'ing a RetainPtr
is not a good idea as it doesn't bump the ref count.

Also protect and friend the CFGAS_GEFont destructor, to make sure
random deletes don't happen.

Also kill off a const cast, and remove unnecessary conversion to
retain_ptr when we already have one.

TEST=look for absence of -11 in XFA corpus test logs, bots not
     currently noticing the segv.  Argh.

Review-Url: https://codereview.chromium.org/2631703003

1 files changed, 4 insertions, 1 deletions

diff --git a/xfa/fxfa/app/xfa_textpiece.cpp b/xfa/fxfa/app/xfa_textpiece.cpp
index 4b57aa82d9..933af6c92f 100644
--- a/xfa/fxfa/app/xfa_textpiece.cpp
+++ b/xfa/fxfa/app/xfa_textpiece.cpp
@@ -9,9 +9,12 @@
 #include "xfa/fxfa/app/cxfa_linkuserdata.h"
 
 XFA_TextPiece::XFA_TextPiece()
-    : pszText(nullptr), pFont(nullptr), pLinkData(nullptr) {}
+    : pszText(nullptr), pWidths(nullptr), pFont(nullptr), pLinkData(nullptr) {}
 
 XFA_TextPiece::~XFA_TextPiece() {
   if (pLinkData)
     pLinkData->Release();
+
+  FX_Free(pszText);
+  FX_Free(pWidths);
 }