Switch from using additional flow steps with a DataFlow::Configuration
in DefaultTaintTracking to using a TaintTracking::Configuration. This
makes future improvements to TaintTracking::Configuration reflected in
DefaultTaintTracking without further effort. It also removes the
predictability constraint in DefaultTaintTracking, which increases the
number of results, with both new true positives and new false positives.
Those may need to be addressed on a per-query basis.
There are some additional regressions from losing pointer/object
conflation for arguments. Those can be worked around by adding that
conflation to TaintTracking::Configuration until precise indirect
parameter flow is ready.
The conflicts came from how `this` is now a parameter but not a
`Parameter` on `master`.
Conflicts:
cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowUtil.qll
cpp/ql/test/library-tests/dataflow/DefaultTaintTracking/defaulttainttracking.cpp
cpp/ql/test/library-tests/dataflow/DefaultTaintTracking/tainted.expected
cpp/ql/test/library-tests/dataflow/DefaultTaintTracking/test_diff.expected
cpp/ql/test/library-tests/dataflow/dataflow-tests/dataflow-ir-consistency.expected
cpp/ql/test/library-tests/dataflow/fields/ir-flow.expected
cpp/ql/test/library-tests/syntax-zoo/dataflow-ir-consistency.expected
After #3382 changed the escape analysis to model qualifiers as escaping,
there was an imbalance in the SSA library, where `addressTakenVariable`
excludes variables from SSA analysis if they have their address taken
but are _not_ passed by reference. This showed up as a missing result in
`TOCTOUFilesystemRace.ql`, demonstrated with a test case in #3432.
This commit changes the definition of "pass by reference" to include
call qualifiers, which allows SSA modeling of variables that have member
function calls on them.
This `select` clause had become very slow after we started caching
`ElementBase::toString` because the query used string concatenation to
produce alert messages, and those string concatenations were done very
early in the pipeline, producing lots of strings that would be discarded
moments later.
By using `$@` to interpolate elements into strings, the concatenation is
done outside of QL.
Testing on a Chromium snapshot, this commit takes us from
#select#ff ................ 6m2s
to
#select#cpe#134#fff ....... 15.2s
