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Merge pull request #20242 from MathiasVP/fprintf-partial-flow

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C++: Mark the write to `fprintf`'s 0'th argument as partial
This commit is contained in:
Mathias Vorreiter Pedersen
2025-08-19 13:43:22 +02:00
committed by GitHub
parent 4684ac1ed9 af00e46fc8
commit ea8d766ae8
6 changed files with 85 additions and 2 deletions
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4
cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/SsaImpl.qll
View File

@@ -756,9 +756,9 @@ private predicate modeledFlowBarrier(Node n) {
partialFlowFunc = call.getStaticCallTarget() and
not partialFlowFunc.isPartialWrite(output)
|
call.getStaticCallTarget().(DataFlow::DataFlowFunction).hasDataFlow(_, output)
partialFlowFunc.(DataFlow::DataFlowFunction).hasDataFlow(_, output)
or
call.getStaticCallTarget().(Taint::TaintFunction).hasTaintFlow(_, output)
partialFlowFunc.(Taint::TaintFunction).hasTaintFlow(_, output)
)
or
exists(Operand operand, Instruction instr, Node n0, int indirectionIndex |

10
cpp/ql/lib/semmle/code/cpp/models/interfaces/FormattingFunction.qll
View File

@@ -170,6 +170,16 @@ abstract class FormattingFunction extends ArrayFunction, TaintFunction {
output.isParameterDeref(this.getOutputParameterIndex(_))
)
}
final override predicate isPartialWrite(FunctionOutput output) {
exists(int outputParameterIndex |
output.isParameterDeref(outputParameterIndex) and
// We require the output to be a stream since that definitely means that
// it's a partial write. If it's not a stream then it will most likely
// fill the whole buffer.
outputParameterIndex = this.getOutputParameterIndex(true)
)
}
}
/**

4
cpp/ql/test/library-tests/dataflow/taint-tests/localTaint.expected
View File

@@ -7767,6 +7767,10 @@ WARNING: module 'TaintTracking' has been deprecated and may be removed in future
| taint.cpp:830:20:830:34 | call to indirect_source | taint.cpp:832:23:832:24 | in | |
| taint.cpp:831:15:831:17 | out | taint.cpp:832:18:832:20 | out | |
| taint.cpp:831:15:831:17 | out | taint.cpp:833:8:833:10 | out | |
| taint.cpp:841:21:841:35 | call to indirect_source | taint.cpp:842:11:842:12 | fp | |
| taint.cpp:841:21:841:35 | call to indirect_source | taint.cpp:843:16:843:17 | fp | |
| taint.cpp:842:11:842:12 | ref arg fp | taint.cpp:843:16:843:17 | fp | |
| taint.cpp:842:15:842:16 | | taint.cpp:842:11:842:12 | ref arg fp | TAINT |
| thread.cpp:10:27:10:27 | s | thread.cpp:10:27:10:27 | s | |
| thread.cpp:10:27:10:27 | s | thread.cpp:11:8:11:8 | s | |
| thread.cpp:14:26:14:26 | s | thread.cpp:15:8:15:8 | s | |

11
cpp/ql/test/library-tests/dataflow/taint-tests/taint.cpp
View File

@@ -831,4 +831,15 @@ void test_write_to_const_ptr_ptr() {
const char* out;
take_const_ptr(out, in);
sink(out); // $ SPURIOUS: ast
}
void indirect_sink(FILE *fp);
int fprintf(FILE *fp, const char *format, ...);
int f7(void)
{
FILE* fp = (FILE*)indirect_source();
fprintf(fp, "");
indirect_sink(fp); // $ ir MISSING: ast
return 0;
}

5
cpp/ql/test/library-tests/dataflow/taint-tests/taint.ql
View File

@@ -117,6 +117,11 @@ module IRTest {
call.getTarget().getName() = "sink" and
[sink.asExpr(), sink.asIndirectExpr()] = call.getAnArgument()
)
or
exists(FunctionCall call |
call.getTarget().getName() = "indirect_sink" and
sink.asIndirectExpr() = call.getAnArgument()
)
}
predicate isBarrier(DataFlow::Node barrier) {

53
cpp/ql/test/library-tests/dataflow/taint-tests/test_mad-signatures.expected
View File

@@ -17670,6 +17670,55 @@ signatureMatches
| taint.cpp:822:6:822:19 | take_const_ptr | (unsigned long *,const char *) | | set_cert_ex | 1 |
| taint.cpp:822:6:822:19 | take_const_ptr | (unsigned long *,const char *) | | set_name_ex | 1 |
| taint.cpp:822:6:822:19 | take_const_ptr | (uv_pipe_t *,const char *) | | uv_pipe_bind | 1 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | _IO_default_uflow | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | _IO_feof | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | _IO_ferror | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | _IO_file_close_mmap | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | _IO_file_underflow_mmap | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | _IO_ftell | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | _IO_getc | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | _IO_getwc | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | _IO_new_file_underflow | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | _IO_peekc_locked | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | _IO_str_count | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | _IO_str_underflow | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | _IO_sungetc | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | _IO_sungetwc | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | _IO_wdefault_uflow | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | _IO_wfile_underflow | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | _IO_wfile_underflow_mmap | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | _IO_wstr_count | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | _IO_wstr_underflow | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | __fbufsize | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | __feof_unlocked | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | __ferror_unlocked | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | __fileno | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | __flbf | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | __fopen_maybe_mmap | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | __fpending | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | __ftello | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | __fwriting | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | __getc_unlocked | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | __getwc_unlocked | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | __uflow | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | __underflow | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | __wuflow | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | __wunderflow | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | feof_unlocked | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | ferror_unlocked | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | fgetc_unlocked | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | fgetgrent | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | fgetpwent | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | fgetsgent | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | fgetspent | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | getc_unlocked | 0 |
| taint.cpp:836:6:836:18 | indirect_sink | (FILE *) | | getmntent | 0 |
| taint.cpp:837:5:837:11 | fprintf | (CURLSH *,CURLSHoption,...) | | curl_share_setopt | 2 |
| taint.cpp:837:5:837:11 | fprintf | (Jim_Interp *,const char *,...) | | Jim_SetResultFormatted | 1 |
| taint.cpp:837:5:837:11 | fprintf | (Jim_Interp *,const char *,...) | | Jim_SetResultFormatted | 2 |
| taint.cpp:837:5:837:11 | fprintf | (char **,const char *,...) | | ___asprintf | 1 |
| taint.cpp:837:5:837:11 | fprintf | (char **,const char *,...) | | ___asprintf | 2 |
| taint.cpp:837:5:837:11 | fprintf | (curl_httppost **,curl_httppost **,...) | | curl_formadd | 2 |
| thread.cpp:4:6:4:9 | sink | (int) | | ASN1_STRING_type_new | 0 |
| thread.cpp:4:6:4:9 | sink | (int) | | ASN1_tag2bit | 0 |
| thread.cpp:4:6:4:9 | sink | (int) | | ASN1_tag2str | 0 |
@@ -47191,6 +47240,10 @@ getParameterTypeName
| taint.cpp:817:6:817:27 | write_to_const_ptr_ptr | 1 | const char ** |
| taint.cpp:822:6:822:19 | take_const_ptr | 0 | const char * |
| taint.cpp:822:6:822:19 | take_const_ptr | 1 | const char * |
| taint.cpp:836:6:836:18 | indirect_sink | 0 | FILE * |
| taint.cpp:837:5:837:11 | fprintf | 0 | FILE * |
| taint.cpp:837:5:837:11 | fprintf | 1 | const char * |
| taint.cpp:837:5:837:11 | fprintf | 2 | ... |
| thread.cpp:4:6:4:9 | sink | 0 | int |
| thread.cpp:6:8:6:8 | operator= | 0 | S && |
| thread.cpp:6:8:6:8 | operator= | 0 | const S & |