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C++: Add a taint model for realloc #14637

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Merged
merged 6 commits into from
Oct 31, 2023
Merged

C++: Add a taint model for realloc #14637

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0837e40
C++: Add failing test.
MathiasVP Oct 30, 2023
08b528b
C++: Add a taint-model for 'realloc' and accept test changes.
MathiasVP Oct 30, 2023
65081a9
C++: Add change note.
MathiasVP Oct 30, 2023
e8c18a3
C++: Add FP in query test.
MathiasVP Oct 31, 2023
4a1bf95
C++: Expose a public memset model and use it in the exposure queries.
MathiasVP Oct 31, 2023
377da9f
C++: Accept test changes.
MathiasVP Oct 31, 2023
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4 changes: 4 additions & 0 deletions cpp/ql/lib/change-notes/2023-10-30-realloc-flow.md
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@@ -0,0 +1,4 @@
---
category: minorAnalysis
---
* Added taint models for `realloc` and related functions.
7 changes: 6 additions & 1 deletion cpp/ql/lib/semmle/code/cpp/models/implementations/Allocation.qll
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Expand Up @@ -5,6 +5,7 @@
*/

import semmle.code.cpp.models.interfaces.Allocation
import semmle.code.cpp.models.interfaces.Taint

/**
* An allocation function (such as `malloc`) that has an argument for the size
Expand Down Expand Up @@ -121,7 +122,7 @@ private class CallocAllocationFunction extends AllocationFunction {
* An allocation function (such as `realloc`) that has an argument for the size
* in bytes, and an argument for an existing pointer that is to be reallocated.
*/
private class ReallocAllocationFunction extends AllocationFunction {
private class ReallocAllocationFunction extends AllocationFunction, TaintFunction {
int sizeArg;
int reallocArg;

Expand Down Expand Up @@ -151,6 +152,10 @@ private class ReallocAllocationFunction extends AllocationFunction {
override int getSizeArg() { result = sizeArg }

override int getReallocPtrArg() { result = reallocArg }

override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
input.isParameterDeref(this.getReallocPtrArg()) and output.isReturnValueDeref()
}
}

/**
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3 changes: 3 additions & 0 deletions cpp/ql/test/library-tests/dataflow/taint-tests/localTaint.expected
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Expand Up @@ -6643,6 +6643,9 @@ WARNING: Module TaintTracking has been deprecated and may be removed in future (
| taint.cpp:729:27:729:32 | endptr | taint.cpp:729:26:729:32 | & ... | |
| taint.cpp:731:7:731:12 | ref arg endptr | taint.cpp:732:8:732:13 | endptr | |
| taint.cpp:732:8:732:13 | endptr | taint.cpp:732:7:732:13 | * ... | TAINT |
| taint.cpp:738:17:738:31 | call to indirect_source | taint.cpp:739:30:739:35 | source | |
| taint.cpp:739:22:739:28 | call to realloc | taint.cpp:740:7:740:10 | dest | |
| taint.cpp:739:30:739:35 | source | taint.cpp:739:22:739:28 | call to realloc | TAINT |
| vector.cpp:16:43:16:49 | source1 | vector.cpp:17:26:17:32 | source1 | |
| vector.cpp:16:43:16:49 | source1 | vector.cpp:31:38:31:44 | source1 | |
| vector.cpp:17:21:17:33 | call to vector | vector.cpp:19:14:19:14 | v | |
Expand Down
8 changes: 8 additions & 0 deletions cpp/ql/test/library-tests/dataflow/taint-tests/taint.cpp
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Expand Up @@ -730,4 +730,12 @@ void test_strtol(char *source) {
sink(l); // $ ast,ir
sink(endptr); // $ ast,ir
sink(*endptr); // $ ast,ir
}

void *realloc(void *, size_t);

void test_realloc() {
char *source = indirect_source();
char *dest = (char*)realloc(source, 16);
sink(dest); // $ ir MISSING: ast
}