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Commit 2a0429b

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author
Nikita Kraiouchkine
committed
Implement InvalidMemory1 queries
Modify packages and implement EXP33-C, EXP34-C, and MEM30-C
1 parent 1c3570d commit 2a0429b
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‎.vscode/tasks.json

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"Includes",
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"Initialization",
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"IntegerConversion",
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"InvalidMemory1",
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"InvalidMemory2",
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"Invariants",
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"Iterators",
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"Lambdas",
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"Literals",
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"Loops",
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"Macros",
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"Memory1",
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"Memory2",
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"Misc",
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"MoveForward",
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"Naming",

‎c/cert/src/rules/EXP33-C/DoNotReadUninitializedMemory.md

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‎c/cert/src/rules/EXP33-C/DoNotReadUninitializedMemory.ql

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/**
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* @id c/cert/do-not-read-uninitialized-memory
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* @name EXP33-C: Do not read uninitialized memory
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* @description Using the value of an object with automatic storage duration while it is
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* indeterminate is undefined behavior.
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* @kind problem
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* @precision medium
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* @problem.severity error
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* @tags external/cert/id/exp33-c
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* correctness
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* security
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* external/cert/obligation/rule
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*/
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import cpp
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import codingstandards.c.cert
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import codingstandards.cpp.rules.readofuninitializedmemory.ReadOfUninitializedMemory
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class DoNotReadUninitializedMemoryQuery extends ReadOfUninitializedMemorySharedQuery {
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DoNotReadUninitializedMemoryQuery() {
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this = InvalidMemory1Package::doNotReadUninitializedMemoryQuery()
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}
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}

‎c/cert/src/rules/EXP34-C/DoNotDereferenceNullPointers.md

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‎c/cert/src/rules/EXP34-C/DoNotDereferenceNullPointers.ql

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/**
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* @id c/cert/do-not-dereference-null-pointers
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* @name EXP34-C: Do not dereference null pointers
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* @description Dereferencing a null pointer leads to undefined behavior.
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* @kind problem
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* @precision medium
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* @problem.severity error
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* @tags external/cert/id/exp34-c
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* correctness
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* external/cert/obligation/rule
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*/
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import cpp
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import codingstandards.c.cert
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import codingstandards.cpp.rules.dereferenceofnullpointer.DereferenceOfNullPointer
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class DoNotDereferenceNullPointersQuery extends DereferenceOfNullPointerSharedQuery {
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DoNotDereferenceNullPointersQuery() {
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this = InvalidMemory1Package::doNotDereferenceNullPointersQuery()
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}
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}

‎c/cert/src/rules/MEM30-C/DoNotAccessFreedMemory.md

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‎c/cert/src/rules/MEM30-C/DoNotAccessFreedMemory.ql

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/**
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* @id c/cert/do-not-access-freed-memory
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* @name MEM30-C: Do not access freed memory
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* @description Accessing memory that has been deallocated is undefined behavior.
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* @kind problem
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* @precision high
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* @problem.severity error
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* @tags external/cert/id/mem30-c
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* correctness
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* security
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* external/cert/obligation/rule
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*/
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import cpp
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import codingstandards.c.cert
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import codingstandards.cpp.Allocations
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import semmle.code.cpp.controlflow.StackVariableReachability
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/** `e` is an expression that frees the memory pointed to by `v`. */
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predicate isFreeExpr(Expr e, StackVariable v) {
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exists(VariableAccess va | va.getTarget() = v and freeExprOrIndirect(e, va, _))
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}
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/** `e` is an expression that (may) dereference `v`. */
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predicate isDerefExpr(Expr e, StackVariable v) {
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v.getAnAccess() = e and dereferenced(e)
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or
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isDerefByCallExpr(_, _, e, v)
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}
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/**
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* `va` is passed by value as (part of) the `i`th argument in
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* call `c`. The target function is either a library function
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* or a source code function that dereferences the relevant
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* parameter.
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*/
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predicate isDerefByCallExpr(Call c, int i, VariableAccess va, StackVariable v) {
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v.getAnAccess() = va and
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va = c.getAnArgumentSubExpr(i) and
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not c.passesByReference(i, va) and
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(c.getTarget().hasEntryPoint() implies isDerefExpr(_, c.getTarget().getParameter(i)))
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}
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class UseAfterFreeReachability extends StackVariableReachability {
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UseAfterFreeReachability() { this = "UseAfterFree" }
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override predicate isSource(ControlFlowNode node, StackVariable v) { isFreeExpr(node, v) }
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override predicate isSink(ControlFlowNode node, StackVariable v) { isDerefExpr(node, v) }
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override predicate isBarrier(ControlFlowNode node, StackVariable v) {
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definitionBarrier(v, node) or
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isFreeExpr(node, v)
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}
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}
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from UseAfterFreeReachability r, StackVariable v, Expr free, Expr e
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where
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not isExcluded(e, InvalidMemory1Package::doNotAccessFreedMemoryQuery()) and
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r.reaches(free, v, e)
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select e,
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"Memory pointed to by '" + v.getName().toString() +
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"' accessed but may have been previously freed $@.", free, "here"

‎c/cert/test/rules/EXP33-C/DoNotReadUninitializedMemory.testref

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c/common/test/rules/readofuninitializedmemory/ReadOfUninitializedMemory.ql

‎c/cert/test/rules/EXP34-C/DoNotDereferenceNullPointers.testref

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c/common/test/rules/dereferenceofnullpointer/DereferenceOfNullPointer.ql

‎c/cert/test/rules/MEM30-C/DoNotAccessFreedMemory.expected

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| test.c:11:47:11:47 | p | Memory pointed to by 'p' accessed but may have been previously freed $@. | test.c:12:5:12:8 | call to free | here |
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| test.c:25:10:25:12 | buf | Memory pointed to by 'buf' accessed but may have been previously freed $@. | test.c:24:3:24:6 | call to free | here |

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