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Merge pull request #2797 from rdmarsh2/rdmarsh/cpp/malloc-alias-locations
C++: Support dynamic memory allocations in IR alias analysis
2 parents 28ee756 + ac517b7 commit ec85f9f

20 files changed

Lines changed: 394 additions & 10 deletions

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‎cpp/ql/src/semmle/code/cpp/ir/implementation/Opcode.qll‎

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Original file line numberDiff line numberDiff line change
@@ -82,6 +82,7 @@ private newtype TOpcode =
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TSizedBufferReadSideEffect() or
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TSizedBufferMustWriteSideEffect() or
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TSizedBufferMayWriteSideEffect() or
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TInitializeDynamicAllocation() or
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TChi() or
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TInlineAsm() or
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TUnreached() or
@@ -695,6 +696,11 @@ module Opcode {
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final override string toString() { result = "SizedBufferMayWriteSideEffect" }
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}
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class InitializeDynamicAllocation extends SideEffectOpcode, EntireAllocationWriteOpcode,
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TInitializeDynamicAllocation {
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final override string toString() { result = "InitializeDynamicAllocation" }
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}
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class Chi extends Opcode, TChi {
699705
final override string toString() { result = "Chi" }
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‎cpp/ql/src/semmle/code/cpp/ir/implementation/aliased_ssa/Instruction.qll‎

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Original file line numberDiff line numberDiff line change
@@ -1350,6 +1350,26 @@ class SizedBufferMayWriteSideEffectInstruction extends WriteSideEffectInstructio
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Instruction getSizeDef() { result = getAnOperand().(BufferSizeOperand).getDef() }
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}
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/**
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* An instruction representing the initial value of newly allocated memory, e.g. the result of a
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* call to `malloc`.
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*/
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class InitializeDynamicAllocationInstruction extends SideEffectInstruction {
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InitializeDynamicAllocationInstruction() {
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getOpcode() instanceof Opcode::InitializeDynamicAllocation
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}
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/**
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* Gets the address of the allocation this instruction is initializing.
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*/
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final AddressOperand getAllocationAddressOperand() { result = getAnOperand() }
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/**
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* Gets the operand for the allocation this instruction is initializing.
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*/
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final Instruction getAllocationAddress() { result = getAllocationAddressOperand().getDef() }
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}
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/**
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* An instruction representing a GNU or MSVC inline assembly statement.
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*/

‎cpp/ql/src/semmle/code/cpp/ir/implementation/aliased_ssa/internal/AliasConfiguration.qll‎

Lines changed: 29 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -7,6 +7,9 @@ private newtype TAllocation =
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TVariableAllocation(IRVariable var) or
88
TIndirectParameterAllocation(IRAutomaticUserVariable var) {
99
exists(InitializeIndirectionInstruction instr | instr.getIRVariable() = var)
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} or
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TDynamicAllocation(CallInstruction call) {
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exists(InitializeDynamicAllocationInstruction instr | instr.getPrimaryInstruction() = call)
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}
1114

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/**
@@ -95,3 +98,29 @@ class IndirectParameterAllocation extends Allocation, TIndirectParameterAllocati
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final override predicate alwaysEscapes() { none() }
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}
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class DynamicAllocation extends Allocation, TDynamicAllocation {
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CallInstruction call;
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DynamicAllocation() { this = TDynamicAllocation(call) }
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final override string toString() {
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result = call.toString() + " at " + call.getLocation() // This isn't performant, but it's only used in test/dump code right now.
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}
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final override CallInstruction getABaseInstruction() { result = call }
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final override IRFunction getEnclosingIRFunction() { result = call.getEnclosingIRFunction() }
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final override Language::Location getLocation() { result = call.getLocation() }
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final override string getUniqueId() { result = call.getUniqueId() }
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final override IRType getIRType() { result instanceof IRUnknownType }
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final override predicate isReadOnly() { none() }
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final override predicate isAlwaysAllocatedOnStack() { none() }
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final override predicate alwaysEscapes() { none() }
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}

‎cpp/ql/src/semmle/code/cpp/ir/implementation/aliased_ssa/internal/AliasedSSA.qll‎

Lines changed: 6 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -68,8 +68,12 @@ private newtype TMemoryLocation =
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) and
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languageType = type.getCanonicalLanguageType()
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} or
71-
TEntireAllocationMemoryLocation(IndirectParameterAllocation var, boolean isMayAccess) {
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isMayAccess = false or isMayAccess = true
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TEntireAllocationMemoryLocation(Allocation var, boolean isMayAccess) {
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(
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var instanceof IndirectParameterAllocation or
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var instanceof DynamicAllocation
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) and
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(isMayAccess = false or isMayAccess = true)
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} or
7478
TUnknownMemoryLocation(IRFunction irFunc, boolean isMayAccess) {
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isMayAccess = false or isMayAccess = true

‎cpp/ql/src/semmle/code/cpp/ir/implementation/raw/Instruction.qll‎

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Original file line numberDiff line numberDiff line change
@@ -1350,6 +1350,26 @@ class SizedBufferMayWriteSideEffectInstruction extends WriteSideEffectInstructio
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Instruction getSizeDef() { result = getAnOperand().(BufferSizeOperand).getDef() }
13511351
}
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/**
1354+
* An instruction representing the initial value of newly allocated memory, e.g. the result of a
1355+
* call to `malloc`.
1356+
*/
1357+
class InitializeDynamicAllocationInstruction extends SideEffectInstruction {
1358+
InitializeDynamicAllocationInstruction() {
1359+
getOpcode() instanceof Opcode::InitializeDynamicAllocation
1360+
}
1361+
1362+
/**
1363+
* Gets the address of the allocation this instruction is initializing.
1364+
*/
1365+
final AddressOperand getAllocationAddressOperand() { result = getAnOperand() }
1366+
1367+
/**
1368+
* Gets the operand for the allocation this instruction is initializing.
1369+
*/
1370+
final Instruction getAllocationAddress() { result = getAllocationAddressOperand().getDef() }
1371+
}
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13531373
/**
13541374
* An instruction representing a GNU or MSVC inline assembly statement.
13551375
*/

‎cpp/ql/src/semmle/code/cpp/ir/implementation/raw/internal/TranslatedCall.qll‎

Lines changed: 23 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -341,16 +341,32 @@ class TranslatedSideEffects extends TranslatedElement, TTranslatedSideEffects {
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)
342342
}
343343

344-
override predicate hasInstruction(Opcode opcode, InstructionTag tag, CppType type) { none() }
345-
346-
override Instruction getFirstInstruction() { result = getChild(0).getFirstInstruction() }
344+
override predicate hasInstruction(Opcode opcode, InstructionTag tag, CppType type) {
345+
expr.getTarget() instanceof AllocationFunction and
346+
opcode instanceof Opcode::InitializeDynamicAllocation and
347+
tag = OnlyInstructionTag() and
348+
type = getUnknownType()
349+
}
347350

348-
override Instruction getInstructionSuccessor(InstructionTag tag, EdgeKind kind) { none() }
351+
override Instruction getFirstInstruction() {
352+
if expr.getTarget() instanceof AllocationFunction
353+
then result = getInstruction(OnlyInstructionTag())
354+
else result = getChild(0).getFirstInstruction()
355+
}
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350-
override Instruction getInstructionOperand(InstructionTag tag, OperandTag operandTag) { none() }
357+
override Instruction getInstructionSuccessor(InstructionTag tag, EdgeKind kind) {
358+
tag = OnlyInstructionTag() and
359+
kind = gotoEdge() and
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expr.getTarget() instanceof AllocationFunction and
361+
if exists(getChild(0))
362+
then result = getChild(0).getFirstInstruction()
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else result = getParent().getChildSuccessor(this)
364+
}
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352-
override CppType getInstructionOperandType(InstructionTag tag, TypedOperandTag operandTag) {
353-
none()
366+
override Instruction getInstructionOperand(InstructionTag tag, OperandTag operandTag) {
367+
tag = OnlyInstructionTag() and
368+
operandTag = addressOperand() and
369+
result = getPrimaryInstructionForSideEffect(OnlyInstructionTag())
354370
}
355371

356372
override Instruction getPrimaryInstructionForSideEffect(InstructionTag tag) {

‎cpp/ql/src/semmle/code/cpp/ir/implementation/raw/internal/TranslatedElement.qll‎

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -411,7 +411,9 @@ newtype TTranslatedElement =
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TTranslatedConditionDecl(ConditionDeclExpr expr) { not ignoreExpr(expr) } or
412412
// The side effects of a `Call`
413413
TTranslatedSideEffects(Call expr) {
414-
exists(TTranslatedArgumentSideEffect(expr, _, _, _)) or expr instanceof ConstructorCall
414+
exists(TTranslatedArgumentSideEffect(expr, _, _, _)) or
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expr instanceof ConstructorCall or
416+
expr.getTarget() instanceof AllocationFunction
415417
} or // A precise side effect of an argument to a `Call`
416418
TTranslatedArgumentSideEffect(Call call, Expr expr, int n, boolean isWrite) {
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(

‎cpp/ql/src/semmle/code/cpp/ir/implementation/unaliased_ssa/Instruction.qll‎

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Original file line numberDiff line numberDiff line change
@@ -1350,6 +1350,26 @@ class SizedBufferMayWriteSideEffectInstruction extends WriteSideEffectInstructio
13501350
Instruction getSizeDef() { result = getAnOperand().(BufferSizeOperand).getDef() }
13511351
}
13521352

1353+
/**
1354+
* An instruction representing the initial value of newly allocated memory, e.g. the result of a
1355+
* call to `malloc`.
1356+
*/
1357+
class InitializeDynamicAllocationInstruction extends SideEffectInstruction {
1358+
InitializeDynamicAllocationInstruction() {
1359+
getOpcode() instanceof Opcode::InitializeDynamicAllocation
1360+
}
1361+
1362+
/**
1363+
* Gets the address of the allocation this instruction is initializing.
1364+
*/
1365+
final AddressOperand getAllocationAddressOperand() { result = getAnOperand() }
1366+
1367+
/**
1368+
* Gets the operand for the allocation this instruction is initializing.
1369+
*/
1370+
final Instruction getAllocationAddress() { result = getAllocationAddressOperand().getDef() }
1371+
}
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13531373
/**
13541374
* An instruction representing a GNU or MSVC inline assembly statement.
13551375
*/

‎cpp/ql/test/library-tests/dataflow/security-taint/tainted.expected‎

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@@ -52,3 +52,18 @@
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| test.cpp:75:20:75:25 | call to getenv | test.cpp:75:15:75:18 | call to atoi | |
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| test.cpp:75:20:75:25 | call to getenv | test.cpp:75:20:75:25 | call to getenv | |
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| test.cpp:75:20:75:25 | call to getenv | test.cpp:75:20:75:45 | (const char *)... | |
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| test.cpp:83:28:83:33 | call to getenv | test.cpp:8:24:8:25 | s1 | |
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| test.cpp:83:28:83:33 | call to getenv | test.cpp:11:20:11:21 | s1 | |
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| test.cpp:83:28:83:33 | call to getenv | test.cpp:11:36:11:37 | s2 | |
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| test.cpp:83:28:83:33 | call to getenv | test.cpp:83:17:83:24 | userName | |
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| test.cpp:83:28:83:33 | call to getenv | test.cpp:83:28:83:33 | call to getenv | |
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| test.cpp:83:28:83:33 | call to getenv | test.cpp:83:28:83:46 | (const char *)... | |
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| test.cpp:83:28:83:33 | call to getenv | test.cpp:85:8:85:11 | copy | |
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| test.cpp:83:28:83:33 | call to getenv | test.cpp:86:2:86:7 | call to strcpy | |
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| test.cpp:83:28:83:33 | call to getenv | test.cpp:86:9:86:12 | copy | |
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| test.cpp:83:28:83:33 | call to getenv | test.cpp:86:15:86:22 | userName | |
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| test.cpp:83:28:83:33 | call to getenv | test.cpp:88:6:88:27 | ! ... | |
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| test.cpp:83:28:83:33 | call to getenv | test.cpp:88:7:88:12 | call to strcmp | |
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| test.cpp:83:28:83:33 | call to getenv | test.cpp:88:7:88:27 | (bool)... | |
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| test.cpp:83:28:83:33 | call to getenv | test.cpp:88:14:88:17 | (const char *)... | |
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| test.cpp:83:28:83:33 | call to getenv | test.cpp:88:14:88:17 | copy | |

‎cpp/ql/test/library-tests/dataflow/security-taint/tainted_diff.expected‎

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@@ -8,3 +8,6 @@
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| test.cpp:68:28:68:33 | call to getenv | test.cpp:69:10:69:13 | copy | AST only |
99
| test.cpp:68:28:68:33 | call to getenv | test.cpp:70:12:70:15 | copy | AST only |
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| test.cpp:68:28:68:33 | call to getenv | test.cpp:71:12:71:15 | copy | AST only |
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| test.cpp:83:28:83:33 | call to getenv | test.cpp:11:20:11:21 | s1 | AST only |
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| test.cpp:83:28:83:33 | call to getenv | test.cpp:85:8:85:11 | copy | AST only |
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| test.cpp:83:28:83:33 | call to getenv | test.cpp:86:9:86:12 | copy | AST only |

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