Verify number of ex flags matches number of ex items.

core/fxcodec/jbig2/JBig2_SddProc.cpp

Index: core/fxcodec/jbig2/JBig2_SddProc.cpp
diff --git a/core/fxcodec/jbig2/JBig2_SddProc.cpp b/core/fxcodec/jbig2/JBig2_SddProc.cpp
index 1a7e96d26b2262ca2d7636a457bcc478d05ae51b..f6afb13497461a30318fcb9f6884380f81cb9c15 100644
--- a/core/fxcodec/jbig2/JBig2_SddProc.cpp
+++ b/core/fxcodec/jbig2/JBig2_SddProc.cpp
@@ -38,6 +38,7 @@ CJBig2_SymbolDict* CJBig2_SDDProc::decode_Arith(
   uint32_t SBNUMSYMS;
   uint8_t SBSYMCODELEN;
   int32_t RDXI, RDYI;
+  uint32_t num_ex_syms;
   CJBig2_Image** SBSYMS;
   std::unique_ptr<CJBig2_ArithIaidDecoder> IAID;
   std::unique_ptr<CJBig2_SymbolDict> pDict;
@@ -235,6 +236,7 @@ CJBig2_SymbolDict* CJBig2_SDDProc::decode_Arith(
   EXINDEX = 0;
   CUREXFLAG = 0;
   EXFLAGS = FX_Alloc(FX_BOOL, SDNUMINSYMS + SDNUMNEWSYMS);
+  num_ex_syms = 0;
   while (EXINDEX < SDNUMINSYMS + SDNUMNEWSYMS) {
     IAEX->decode(pArithDecoder, (int*)&EXRUNLENGTH);
     if (EXINDEX + EXRUNLENGTH > SDNUMINSYMS + SDNUMNEWSYMS) {
@@ -243,12 +245,19 @@ CJBig2_SymbolDict* CJBig2_SDDProc::decode_Arith(
     }
     if (EXRUNLENGTH != 0) {
       for (I = EXINDEX; I < EXINDEX + EXRUNLENGTH; I++) {
+        if (CUREXFLAG)
+          num_ex_syms++;
         EXFLAGS[I] = CUREXFLAG;
       }
     }
     EXINDEX = EXINDEX + EXRUNLENGTH;
     CUREXFLAG = !CUREXFLAG;
   }
+  if (num_ex_syms > SDNUMEXSYMS) {
+    FX_Free(EXFLAGS);
+    goto failed;
+  }
+
   pDict.reset(new CJBig2_SymbolDict);
   I = J = 0;
   for (I = 0; I < SDNUMINSYMS + SDNUMNEWSYMS; I++) {
@@ -303,6 +312,7 @@ CJBig2_SymbolDict* CJBig2_SDDProc::decode_Huffman(
   int32_t RDXI, RDYI;
   uint32_t BMSIZE;
   uint32_t stride;
+  uint32_t num_ex_syms;
   CJBig2_Image** SBSYMS;
   std::unique_ptr<CJBig2_HuffmanDecoder> pHuffmanDecoder(
       new CJBig2_HuffmanDecoder(pStream));
@@ -555,6 +565,7 @@ CJBig2_SymbolDict* CJBig2_SDDProc::decode_Huffman(
   pTable.reset(new CJBig2_HuffmanTable(HuffmanTable_B1, HuffmanTable_B1_Size,
                                        HuffmanTable_HTOOB_B1));
   EXFLAGS = FX_Alloc(FX_BOOL, SDNUMINSYMS + SDNUMNEWSYMS);
+  num_ex_syms = 0;
   while (EXINDEX < SDNUMINSYMS + SDNUMNEWSYMS) {
     if (pHuffmanDecoder->decodeAValue(pTable.get(), (int*)&EXRUNLENGTH) != 0) {
       FX_Free(EXFLAGS);
@@ -566,12 +577,20 @@ CJBig2_SymbolDict* CJBig2_SDDProc::decode_Huffman(
     }
     if (EXRUNLENGTH != 0) {
       for (I = EXINDEX; I < EXINDEX + EXRUNLENGTH; I++) {
+        if (CUREXFLAG)
+          num_ex_syms++;
+
         EXFLAGS[I] = CUREXFLAG;
       }
     }
     EXINDEX = EXINDEX + EXRUNLENGTH;
     CUREXFLAG = !CUREXFLAG;
   }
+  if (num_ex_syms > SDNUMEXSYMS) {
+    FX_Free(EXFLAGS);
+    goto failed;
+  }
+
   I = J = 0;
   for (I = 0; I < SDNUMINSYMS + SDNUMNEWSYMS; I++) {
     if (EXFLAGS[I] && J < SDNUMEXSYMS) {