commit 5c1a60445e32c5c80574bf5e806fc2d75dd852ea
author Tom Sepez <tsepez@chromium.org> Tue Jul 20 16:02:05 2021 +0000
committer Pdfium LUCI CQ <pdfium-scoped@luci-project-accounts.iam.gserviceaccount.com> Tue Jul 20 16:02:05 2021 +0000
tree 808b8de35f41088247478249bfdcf984b5856d45
parent 0eb31ab0485640715d0c310716d8e984df2a8c3c

Use more FXSYS_*_GET_MSBFIRST macros

Avoids possible UB issues when uint8_t with high bit set gets
widened to int, then shifted by 24.

Change-Id: I84c757e214247d46ea35e39c4d52842bc23e967c
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/82977
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>

core/fpdfapi/font/cfx_cttgsubtable.cpp

diff --git a/core/fpdfapi/font/cfx_cttgsubtable.cpp b/core/fpdfapi/font/cfx_cttgsubtable.cpp
index bad7f71..f79484f 100644
--- a/core/fpdfapi/font/cfx_cttgsubtable.cpp
+++ b/core/fpdfapi/font/cfx_cttgsubtable.cpp
@@ -147,25 +147,25 @@
 }
 
 int16_t CFX_CTTGSUBTable::GetInt16(FT_Bytes& p) const {
-  uint16_t ret = p[0] << 8 | p[1];
+  uint16_t ret = FXSYS_UINT16_GET_MSBFIRST(p);
   p += 2;
   return *(int16_t*)&ret;
 }
 
 uint16_t CFX_CTTGSUBTable::GetUInt16(FT_Bytes& p) const {
-  uint16_t ret = p[0] << 8 | p[1];
+  uint16_t ret = FXSYS_UINT16_GET_MSBFIRST(p);
   p += 2;
   return ret;
 }
 
 int32_t CFX_CTTGSUBTable::GetInt32(FT_Bytes& p) const {
-  uint32_t ret = p[0] << 24 | p[1] << 16 | p[2] << 8 | p[3];
+  uint32_t ret = FXSYS_UINT32_GET_MSBFIRST(p);
   p += 4;
   return *(int32_t*)&ret;
 }
 
 uint32_t CFX_CTTGSUBTable::GetUInt32(FT_Bytes& p) const {
-  uint32_t ret = p[0] << 24 | p[1] << 16 | p[2] << 8 | p[3];
+  uint32_t ret = FXSYS_UINT32_GET_MSBFIRST(p);
   p += 4;
   return ret;
 }

core/fxcodec/basic/basicmodule.cpp

diff --git a/core/fxcodec/basic/basicmodule.cpp b/core/fxcodec/basic/basicmodule.cpp
index 6cb8eb3..13678ff 100644
--- a/core/fxcodec/basic/basicmodule.cpp
+++ b/core/fxcodec/basic/basicmodule.cpp
@@ -330,10 +330,8 @@
   uint32_t pos = 0;
   uint32_t line_length = 0;
   while (src_span.size() >= 4 && pos < src_span.size() - 3) {
-    uint32_t val = ((uint32_t)(src_span[pos]) << 24) +
-                   ((uint32_t)(src_span[pos + 1]) << 16) +
-                   ((uint32_t)(src_span[pos + 2]) << 8) +
-                   (uint32_t)(src_span[pos + 3]);
+    auto val_span = src_span.subspan(pos, 4);
+    uint32_t val = FXSYS_UINT32_GET_MSBFIRST(val_span);
     pos += 4;
     if (val == 0) {  // All zero special case
       *out = 'z';

xfa/fgas/font/cfgas_fontmgr.cpp

diff --git a/xfa/fgas/font/cfgas_fontmgr.cpp b/xfa/fgas/font/cfgas_fontmgr.cpp
index d30ae44..91c2e99 100644
--- a/xfa/fgas/font/cfgas_fontmgr.cpp
+++ b/xfa/fgas/font/cfgas_fontmgr.cpp
@@ -15,6 +15,7 @@
 #include "core/fxcrt/fx_codepage.h"
 #include "core/fxcrt/fx_extension.h"
 #include "core/fxcrt/fx_memory_wrappers.h"
+#include "core/fxcrt/fx_system.h"
 #include "core/fxge/cfx_font.h"
 #include "core/fxge/cfx_fontmapper.h"
 #include "core/fxge/cfx_fontmgr.h"
@@ -337,7 +338,7 @@
 }
 
 inline uint16_t GetUInt16(const uint8_t* p) {
-  return static_cast<uint16_t>(p[0] << 8 | p[1]);
+  return FXSYS_UINT16_GET_MSBFIRST(p);
 }
 
 extern "C" {