Bounds check before fixed-size memcmp() in CJPX_Decoder::Init().

core/src/fxcodec/codec/fx_codec_jpx_opj.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
  
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "../../../include/fxcodec/fx_codec.h"
 #include "codec_int.h"
 #include "../fx_libopenjpeg/libopenjpeg20/openjpeg.h"
 #include "../lcms2/include/fx_lcms2.h"
+namespace {
+const char ExpectedJP2Header[] = "\x00\x00\x00\x0c\x6a\x50\x20\x20\x0d\x0a\x87\x0a";
+const size_t ExpectedJP2HeaderSize = sizeof(ExpectedJP2Header) - 1;

[jun_fang, 2014/08/26 22:09:15]

are you sure that it needs to subtract 1 (-1)? sizeof(array) indicates the
actual length of an array.

+}  // namespace
 static void fx_error_callback(const char *msg, void *client_data)
 {
     (void)client_data;
 }
 static void fx_warning_callback(const char *msg, void *client_data)
 {
     (void)client_data;
 }
 static void fx_info_callback(const char *msg, void *client_data)
 {
@@ skipping 553 matching lines @@
     }
     if(l_stream) {
         opj_stream_destroy(l_stream);
     }
     if(image) {
         opj_image_destroy(image);
     }
 }
 FX_BOOL CJPX_Decoder::Init(const unsigned char* src_data, int src_size)
 {
-    opj_dparameters_t parameters;
+    if (!src_data || src_size < ExpectedJP2HeaderSize) {
+        return FALSE;
+    }
     image = NULL;
     m_SrcData = src_data;
     m_SrcSize = src_size;
     decodeData srcData;
     srcData.offset  = 0;
     srcData.src_size = src_size;
     srcData.src_data = src_data;
     l_stream = fx_opj_stream_create_memory_stream(&srcData, OPJ_J2K_STREAM_CHUNK_SIZE, 1);
     if (l_stream == NULL) {
         return FALSE;
     }
+    opj_dparameters_t parameters;
     opj_set_default_decoder_parameters(&parameters);
     parameters.decod_format = 0;
     parameters.cod_format = 3;
-    if(FXSYS_memcmp32(m_SrcData, "\x00\x00\x00\x0c\x6a\x50\x20\x20\x0d\x0a\x87\x0a", 12) == 0) {
+    if(FXSYS_memcmp32(m_SrcData, ExpectedJP2Header, ExpectedJP2HeaderSize) == 0) {
         l_codec = opj_create_decompress(OPJ_CODEC_JP2);
         parameters.decod_format = 1;
     } else {
         l_codec = opj_create_decompress(OPJ_CODEC_J2K);
     }
     if(!l_codec) {
         return FALSE;
     }
     opj_set_info_handler(l_codec, fx_info_callback, 00);
     opj_set_warning_handler(l_codec, fx_warning_callback, 00);
@@ skipping 172 matching lines @@
 FX_BOOL CCodec_JpxModule::Decode(void* ctx, FX_LPBYTE dest_data, int pitch, FX_BOOL bTranslateColor, FX_LPBYTE offsets)
 {
     CJPX_Decoder* pDecoder = (CJPX_Decoder*)ctx;
     return pDecoder->Decode(dest_data, pitch, bTranslateColor, offsets);
 }
 void CCodec_JpxModule::DestroyDecoder(void* ctx)
 {
     CJPX_Decoder* pDecoder = (CJPX_Decoder*)ctx;
     delete pDecoder;
 }