Replace undefined shift operations by multiplications

Shift operations are undefined for negative numbers, but at least on
Intel they return the same value as a multiplication with 2 ^ shift value.

This fixes runtime errors reported by sanitizers and OSS-Fuzz:

    intmatcher.cpp:821:59: runtime error: left shift of negative value -14
    intmatcher.cpp:823:75: runtime error: left shift of negative value -512
    intmatcher.cpp:820:50: runtime error: left shift of negative value -80

See issue #2297 and
https://oss-fuzz.com/testcase-detail/4845195990925312 for details.

Signed-off-by: Stefan Weil <[email protected]>

Author: stweil

src/classify/intmatcher.cpp

@@ -774,13 +774,6 @@ int IntegerMatcher::UpdateTablesForFeature(
   uint32_t XFeatureAddress;
   uint32_t YFeatureAddress;
   uint32_t ThetaFeatureAddress;
-  int ProtoIndex;
-  uint8_t Temp;
-  int* IntPointer;
-  int ConfigNum;
-  int32_t M3;
-  int32_t A3;
-  uint32_t A4;
 
   tables->ClearFeatureEvidence(ClassTemplate);
 
@@ -816,10 +809,10 @@ int IntegerMatcher::UpdateTablesForFeature(
           proto_byte = next_table[proto_byte];
           Proto = &(ProtoSet->Protos[ProtoNum + proto_offset]);
           ConfigWord = Proto->Configs[0];
-          A3 = (((Proto->A * (Feature->X - 128)) << 1)
-            - (Proto->B * (Feature->Y - 128)) + (Proto->C << 9));
-          M3 =
-            (((int8_t) (Feature->Theta - Proto->Angle)) * kIntThetaFudge) << 1;
+          int32_t A3 = (((Proto->A * (Feature->X - 128)) * 2)
+            - (Proto->B * (Feature->Y - 128)) + (Proto->C * 512));
+          int32_t M3 = ((static_cast<int8_t>(Feature->Theta - Proto->Angle)) *
+                        kIntThetaFudge) * 2;
 
           if (A3 < 0)
             A3 = ~A3;
@@ -832,7 +825,7 @@ int IntegerMatcher::UpdateTablesForFeature(
           if (static_cast<uint32_t>(M3) > evidence_mult_mask_)
             M3 = evidence_mult_mask_;
 
-          A4 = (A3 * A3) + (M3 * M3);
+          uint32_t A4 = (A3 * A3) + (M3 * M3);
           A4 >>= table_trunc_shift_bits_;
           if (A4 > evidence_table_mask_)
             Evidence = 0;
@@ -863,11 +856,11 @@ int IntegerMatcher::UpdateTablesForFeature(
 
           uint8_t* UINT8Pointer =
             &(tables->proto_evidence_[ActualProtoNum + proto_offset][0]);
-          for (ProtoIndex =
+          for (int ProtoIndex =
             ClassTemplate->ProtoLengths[ActualProtoNum + proto_offset];
           ProtoIndex > 0; ProtoIndex--, UINT8Pointer++) {
             if (Evidence > *UINT8Pointer) {
-              Temp = *UINT8Pointer;
+              uint8_t Temp = *UINT8Pointer;
               *UINT8Pointer = Evidence;
               Evidence = Temp;
             }
@@ -884,10 +877,10 @@ int IntegerMatcher::UpdateTablesForFeature(
                             ClassTemplate->NumConfigs);
   }
 
-  IntPointer = tables->sum_feature_evidence_;
+  int* IntPointer = tables->sum_feature_evidence_;
   uint8_t* UINT8Pointer = tables->feature_evidence_;
   int SumOverConfigs = 0;
-  for (ConfigNum = ClassTemplate->NumConfigs; ConfigNum > 0; ConfigNum--) {
+  for (int ConfigNum = ClassTemplate->NumConfigs; ConfigNum > 0; ConfigNum--) {
     int evidence = *UINT8Pointer++;
     SumOverConfigs += evidence;
     *IntPointer++ += evidence;