diff --git a/core/fxcodec/jbig2/JBig2_ArithIntDecoder.cpp b/core/fxcodec/jbig2/JBig2_ArithIntDecoder.cpp
index 7ed7702..8ef1e0d 100644
--- a/core/fxcodec/jbig2/JBig2_ArithIntDecoder.cpp
+++ b/core/fxcodec/jbig2/JBig2_ArithIntDecoder.cpp
@@ -53,6 +53,9 @@
   // Decoding Procedure" on page 113 of the JBIG2 specification (ISO/IEC FCD
   // 14492).
   int PREV = 1;
+  if (pArithDecoder->IsComplete())
+    return false;
+
   const int S = pArithDecoder->DECODE(&m_IAx[PREV]);
   PREV = ShiftOr(PREV, S);
 
@@ -61,6 +64,9 @@
 
   int nTemp = 0;
   for (int i = 0; i < g_ArithIntDecodeData[nDecodeDataIndex].nNeedBits; ++i) {
+    if (pArithDecoder->IsComplete())
+      return false;
+
     int D = pArithDecoder->DECODE(&m_IAx[PREV]);
     PREV = ShiftOr(PREV, D);
     if (PREV >= 256)
@@ -92,13 +98,17 @@
 
 CJBig2_ArithIaidDecoder::~CJBig2_ArithIaidDecoder() {}
 
-void CJBig2_ArithIaidDecoder::decode(CJBig2_ArithDecoder* pArithDecoder,
+bool CJBig2_ArithIaidDecoder::decode(CJBig2_ArithDecoder* pArithDecoder,
                                      uint32_t* nResult) {
   int PREV = 1;
   for (unsigned char i = 0; i < SBSYMCODELEN; ++i) {
     JBig2ArithCtx* pCX = &m_IAID[PREV];
+    if (pArithDecoder->IsComplete())
+      return false;
+
     int D = pArithDecoder->DECODE(pCX);
     PREV = ShiftOr(PREV, D);
   }
   *nResult = PREV - (1 << SBSYMCODELEN);
+  return true;
 }
diff --git a/core/fxcodec/jbig2/JBig2_ArithIntDecoder.h b/core/fxcodec/jbig2/JBig2_ArithIntDecoder.h
index fd9fa89..2de42a0 100644
--- a/core/fxcodec/jbig2/JBig2_ArithIntDecoder.h
+++ b/core/fxcodec/jbig2/JBig2_ArithIntDecoder.h
@@ -17,8 +17,7 @@
   CJBig2_ArithIntDecoder();
   ~CJBig2_ArithIntDecoder();
 
-  // Returns true on success, and false when an OOB condition occurs. Many
-  // callers can tolerate OOB and do not check the return value.
+  // Returns true on success, and false when an OOB condition occurs.
   bool decode(CJBig2_ArithDecoder* pArithDecoder, int* nResult);
 
  private:
@@ -30,7 +29,7 @@
   explicit CJBig2_ArithIaidDecoder(unsigned char SBSYMCODELENA);
   ~CJBig2_ArithIaidDecoder();
 
-  void decode(CJBig2_ArithDecoder* pArithDecoder, uint32_t* nResult);
+  bool decode(CJBig2_ArithDecoder* pArithDecoder, uint32_t* nResult);
 
  private:
   std::vector<JBig2ArithCtx> m_IAID;
diff --git a/core/fxcodec/jbig2/JBig2_SddProc.cpp b/core/fxcodec/jbig2/JBig2_SddProc.cpp
index 45aa22e..43768bd 100644
--- a/core/fxcodec/jbig2/JBig2_SddProc.cpp
+++ b/core/fxcodec/jbig2/JBig2_SddProc.cpp
@@ -68,7 +68,9 @@
   NSYMSDECODED = 0;
   while (NSYMSDECODED < SDNUMNEWSYMS) {
     std::unique_ptr<CJBig2_Image> BS;
-    IADH->decode(pArithDecoder, &HCDH);
+    if (!IADH->decode(pArithDecoder, &HCDH))
+      return nullptr;
+
     HCHEIGHT = HCHEIGHT + HCDH;
     if ((int)HCHEIGHT < 0 || (int)HCHEIGHT > JBIG2_MAX_IMAGE_SIZE)
       return nullptr;
@@ -113,7 +115,8 @@
         if (!BS)
           return nullptr;
       } else {
-        IAAI->decode(pArithDecoder, (int*)&REFAGGNINST);
+        if (!IAAI->decode(pArithDecoder, reinterpret_cast<int*>(&REFAGGNINST)))
+          return nullptr;
         if (REFAGGNINST > 1) {
           auto pDecoder = pdfium::MakeUnique<CJBig2_TRDProc>();
           pDecoder->SBHUFF = SDHUFF;
@@ -186,12 +189,11 @@
         } else if (REFAGGNINST == 1) {
           SBNUMSYMS = SDNUMINSYMS + NSYMSDECODED;
           uint32_t IDI;
-          IAID->decode(pArithDecoder, &IDI);
-          IARDX->decode(pArithDecoder, &RDXI);
-          IARDY->decode(pArithDecoder, &RDYI);
-          if (IDI >= SBNUMSYMS)
+          if (!IAID->decode(pArithDecoder, &IDI) ||
+              !IARDX->decode(pArithDecoder, &RDXI) ||
+              !IARDY->decode(pArithDecoder, &RDYI) || IDI >= SBNUMSYMS) {
             return nullptr;
-
+          }
           SBSYMS.resize(SBNUMSYMS);
           std::copy(SDINSYMS, SDINSYMS + SDNUMINSYMS, SBSYMS.begin());
           for (size_t i = 0; i < NSYMSDECODED; ++i)
@@ -225,10 +227,10 @@
   EXFLAGS.resize(SDNUMINSYMS + SDNUMNEWSYMS);
   num_ex_syms = 0;
   while (EXINDEX < SDNUMINSYMS + SDNUMNEWSYMS) {
-    IAEX->decode(pArithDecoder, (int*)&EXRUNLENGTH);
-    if (EXINDEX + EXRUNLENGTH > SDNUMINSYMS + SDNUMNEWSYMS)
+    if (!IAEX->decode(pArithDecoder, (int*)&EXRUNLENGTH) ||
+        EXINDEX + EXRUNLENGTH > SDNUMINSYMS + SDNUMNEWSYMS) {
       return nullptr;
-
+    }
     if (EXRUNLENGTH != 0) {
       for (I = EXINDEX; I < EXINDEX + EXRUNLENGTH; I++) {
         if (CUREXFLAG)
diff --git a/core/fxcodec/jbig2/JBig2_TrdProc.cpp b/core/fxcodec/jbig2/JBig2_TrdProc.cpp
index 332e586..78eb780 100644
--- a/core/fxcodec/jbig2/JBig2_TrdProc.cpp
+++ b/core/fxcodec/jbig2/JBig2_TrdProc.cpp
@@ -281,7 +281,9 @@
     for (;;) {
       if (bFirst) {
         int32_t DFS;
-        pIAFS->decode(pArithDecoder, &DFS);
+        if (!pIAFS->decode(pArithDecoder, &DFS))
+          return nullptr;
+
         FIRSTS += DFS;
         CURS = FIRSTS;
         bFirst = false;
@@ -297,8 +299,10 @@
         break;
 
       int CURT = 0;
-      if (SBSTRIPS != 1)
-        pIAIT->decode(pArithDecoder, &CURT);
+      if (SBSTRIPS != 1) {
+        if (!pIAIT->decode(pArithDecoder, &CURT))
+          return nullptr;
+      }
 
       FX_SAFE_INT32 SAFE_TI = STRIPT + CURT;
       if (!SAFE_TI.IsValid())
@@ -306,15 +310,16 @@
 
       int32_t TI = SAFE_TI.ValueOrDie();
       uint32_t IDI;
-      pIAID->decode(pArithDecoder, &IDI);
-      if (IDI >= SBNUMSYMS)
+      if (!pIAID->decode(pArithDecoder, &IDI) || IDI >= SBNUMSYMS)
         return nullptr;
 
       int RI;
-      if (SBREFINE == 0)
+      if (SBREFINE == 0) {
         RI = 0;
-      else
-        pIARI->decode(pArithDecoder, &RI);
+      } else {
+        if (!pIARI->decode(pArithDecoder, &RI))
+          return nullptr;
+      }
 
       MaybeOwned<CJBig2_Image> pIBI;
       if (RI == 0) {
@@ -324,10 +329,12 @@
         int32_t RDHI;
         int32_t RDXI;
         int32_t RDYI;
-        pIARDW->decode(pArithDecoder, &RDWI);
-        pIARDH->decode(pArithDecoder, &RDHI);
-        pIARDX->decode(pArithDecoder, &RDXI);
-        pIARDY->decode(pArithDecoder, &RDYI);
+        if (!pIARDW->decode(pArithDecoder, &RDWI) ||
+            !pIARDH->decode(pArithDecoder, &RDHI) ||
+            !pIARDX->decode(pArithDecoder, &RDXI) ||
+            !pIARDY->decode(pArithDecoder, &RDYI)) {
+          return nullptr;
+        }
         CJBig2_Image* IBOI = SBSYMS[IDI];
         if (!IBOI)
           return nullptr;