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Code Issues Releases Wiki Activity

Restrict distribution producing non-multiples if no sub-components

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This commit is contained in:
caheckman 2020-04-30 18:38:01 -04:00
parent 40bb05d8ed
commit 4f1adfcfc0
2 changed files with 16 additions and 9 deletions
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24
Ghidra/Features/Decompiler/src/decompile/cpp/ruleaction.cc
View file

@ -5626,7 +5626,8 @@ AddTreeState::AddTreeState(Funcdata &d,PcodeOp *op,int4 slot)
ct = (const TypePointer *)ptr->getType();
ptrsize = ptr->getSize();
ptrmask = calc_mask(ptrsize);
size = AddrSpace::byteToAddressInt(ct->getPtrTo()->getSize(),ct->getWordSize());
baseType = ct->getPtrTo();
size = AddrSpace::byteToAddressInt(baseType->getSize(),ct->getWordSize());
multsum = 0; // Sums start out as zero
nonmultsum = 0;
correct = 0;
@ -5701,16 +5702,21 @@ bool AddTreeState::checkTerm(Varnode *vn,uintb treeCoeff)
if (vn == ptr) return false;
if (vn->isConstant()) {
if (treeCoeff != 1)
isDistributeUsed = true;
val = vn->getOffset() * treeCoeff;
intb sval = (intb)val;
sign_extend(sval,vn->getSize()*8-1);
intb rem = (size == 0) ? sval : (sval % size);
if (rem!=0) { // constant is not multiple of size
if (treeCoeff != 1) {
// An offset "into" the base data-type makes little sense unless is has subcomponents
if (baseType->getMetatype() == TYPE_ARRAY || baseType->getMetatype() == TYPE_STRUCT)
isDistributeUsed = true;
}
nonmultsum += val;
return true;
}
if (treeCoeff != 1)
isDistributeUsed = true;
multsum += val; // Add multiples of size into multsum
return false;
}
@ -5786,11 +5792,11 @@ void AddTreeState::calcSubtype(void)
}
isSubtype = false; // There are no offsets INTO the pointer
}
else if (ct->getPtrTo()->getMetatype() == TYPE_SPACEBASE) {
else if (baseType->getMetatype() == TYPE_SPACEBASE) {
uintb nonmultbytes = AddrSpace::addressToByte(nonmultsum,ct->getWordSize()); // Convert to bytes
uintb extra;
// Get offset into mapped variable
if (ct->getPtrTo()->getSubType(nonmultbytes, &extra) == (Datatype*)0) {
if (baseType->getSubType(nonmultbytes, &extra) == (Datatype*)0) {
valid = false; // Cannot find mapped variable but nonmult is non-empty
return;
}
@ -5798,12 +5804,12 @@ void AddTreeState::calcSubtype(void)
offset = (nonmultsum - extra) & ptrmask;
isSubtype = true;
}
else if (ct->getPtrTo()->getMetatype() == TYPE_STRUCT) {
else if (baseType->getMetatype() == TYPE_STRUCT) {
uintb nonmultbytes = AddrSpace::addressToByte(nonmultsum,ct->getWordSize()); // Convert to bytes
uintb extra;
// Get offset into field in structure
if (ct->getPtrTo()->getSubType(nonmultbytes, &extra) == (Datatype*) 0) {
if (nonmultbytes >= ct->getPtrTo()->getSize()) {
if (baseType->getSubType(nonmultbytes, &extra) == (Datatype*) 0) {
if (nonmultbytes >= size) {
valid = false; // Out of structure's bounds
return;
}
@ -5813,7 +5819,7 @@ void AddTreeState::calcSubtype(void)
offset = (nonmultsum - extra) & ptrmask;
isSubtype = true;
}
else if (ct->getPtrTo()->getMetatype() == TYPE_ARRAY) {
else if (baseType->getMetatype() == TYPE_ARRAY) {
isSubtype = true;
offset = 0;
}

1
Ghidra/Features/Decompiler/src/decompile/cpp/ruleaction.hh
View file

@ -44,6 +44,7 @@ class AddTreeState {
PcodeOp *baseOp; ///< Base of the ADD tree
Varnode *ptr; ///< The pointer varnode
const TypePointer *ct; ///< The pointer data-type
const Datatype *baseType; ///< The base data-type being pointed at
int4 ptrsize; ///< Size of the pointer
int4 size; ///< Size of data-type being pointed to
uintb ptrmask; ///< Mask for modulo calculations in ptr space