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C++: Clean up false-positives

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C++: Change note
This commit is contained in:
Calum Grant
2024-10-14 17:10:55 +01:00
parent fe85e007b3
commit 853128c9c3
6 changed files with 16 additions and 13 deletions
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4
cpp/ql/lib/semmle/code/cpp/models/implementations/Printf.qll
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@@ -50,6 +50,8 @@ private class Fprintf extends FormattingFunction, NonThrowingFunction {
override int getFormatParameterIndex() { result = 1 }
override int getOutputParameterIndex(boolean isStream) { result = 0 and isStream = true }
override int getFirstFormatArgumentIndex() { result = 2 }
}
/**
@@ -91,7 +93,7 @@ private class Sprintf extends FormattingFunction, NonThrowingFunction {
override int getFirstFormatArgumentIndex() {
if this.hasName("__builtin___sprintf_chk")
then result = 4
else result = this.getNumberOfParameters()
else result = this.getNumberOfExplicitParameters()
}
}

2
cpp/ql/lib/semmle/code/cpp/models/interfaces/FormattingFunction.qll
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@@ -143,7 +143,7 @@ abstract class FormattingFunction extends ArrayFunction, TaintFunction {
* from implicit function declarations. If there is some inconsistency in the number
* of parameters, then don't return anything.
*/
private int getNumberOfExplicitParameters() {
int getNumberOfExplicitParameters() {
forex(FunctionDeclarationEntry fde | fde = this.getAnExplicitDeclarationEntry() |
result = fde.getNumberOfParameters()
)

3
cpp/ql/src/Likely Bugs/Format/WrongTypeFormatArguments.ql
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@@ -170,7 +170,8 @@ where
) and
not arg.isAffectedByMacro() and
not arg.isFromUninstantiatedTemplate(_) and
not actual.getUnspecifiedType() instanceof ErroneousType
not actual.getUnspecifiedType() instanceof ErroneousType and
not arg.(Call).getTarget().getADeclarationEntry().isImplicit()
select arg,
"This format specifier for type '" + expected.getName() + "' does not match the argument type '" +
actual.getUnspecifiedType().getName() + "'."

4
cpp/ql/src/change-notes/2024-10-15-wrong-type-format-argument.md Normal file
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@@ -0,0 +1,4 @@
---
category: minorAnalysis
---
* Fixed false positives in the `cpp/wrong-type-format-argument` ("Wrong type of arguments to formatting function") query if there are extraction errors in the function.

5
cpp/ql/test/query-tests/Likely Bugs/Format/WrongTypeFormatArguments/Buildless/WrongTypeFormatArguments.expected
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@@ -1,4 +1 @@
| tests.c:7:18:7:18 | 1 | This format specifier for type 'char *' does not match the argument type 'int'. |
| tests.c:8:18:8:34 | call to implicit_function | This format specifier for type 'char *' does not match the argument type 'int'. |
| tests.c:9:13:9:13 | 0 | This format specifier for type 'char *' does not match the argument type 'int'. |
| tests.c:10:13:10:13 | 0 | This format specifier for type 'char *' does not match the argument type 'int'. |
| tests.c:6:18:6:18 | 1 | This format specifier for type 'char *' does not match the argument type 'int'. |

11
cpp/ql/test/query-tests/Likely Bugs/Format/WrongTypeFormatArguments/Buildless/tests.c
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@@ -1,11 +1,10 @@
// semmle-extractor-options: --expect_errors
int printf(const char * format, ...);
int fprintf();
int f() {
printf("%s", 1); // BAD - TP
printf("%s", implicit_function()); // BAD (FP) - we should not infer the return type
sprintf(0, "%s", ""); // BAD (FP)
fprintf(0, "%s", ""); // BAD (FP)
void f() {
printf("%s", 1); // BAD
printf("%s", implicit_function()); // GOOD - we should ignore the type
sprintf(0, "%s", ""); // GOOD
fprintf(0, "%s", ""); // GOOD
}