We now have symbols with floating-point type to make sure that
(double)x == (double)x comes out true, but we still can't do much with
these. For now, don't even bother trying to create a floating-point zero
value; just give up on conversion to bool.
PR14634, C++ edition.
llvm-svn: 190953
When casting the address of a FunctionTextRegion to bool, or when adding
constraints to such an address, use a stand-in symbol to represent the
presence or absence of the function if the function is weakly linked.
This is groundwork for possible simple availability testing checks, and
can already catch mistakes involving inverted null checks for
weakly-linked functions.
Currently, the implementation reuses the "extent" symbols, originally created
for tracking the size of a malloc region. Since FunctionTextRegions cannot
be dereferenced, the extent symbol will never be used for anything else.
Still, this probably deserves a refactoring in the future.
This patch does not attempt to support testing the presence of weak
/variables/ (global variables), which would likely require much more of
a change and a generalization of "region structure metadata", like the
current "extents", vs. "region contents metadata", like CStringChecker's
"string length".
Patch by Richard <tarka.t.otter@googlemail.com>!
llvm-svn: 189492
Previously, SValBuilder knew how to evaluate StringLiterals, but couldn't
handle an array-to-pointer decay for constant values. Additionally,
RegionStore was being too strict about loading from an array, refusing to
return a 'char' value from a 'const char' array. Both of these have been
fixed.
llvm-svn: 186520
This gives slightly better precision, specifically, in cases where a non-typed region represents the array
or when the type is a non-array type, which can happen when an array is a result of a reinterpret_cast.
llvm-svn: 182810
...and don't consider '0' to be a null pointer constant if it's the
initializer for a float!
Apparently null pointer constant evaluation looks through both
MaterializeTemporaryExpr and ImplicitCastExpr, so we have to be more
careful about types in the callers. For RegionStore this just means giving
up a little more; for ExprEngine this means handling the
MaterializeTemporaryExpr case explicitly.
Follow-up to r180894.
llvm-svn: 180944
Previously, this was scattered across Environment (literal expressions),
ExprEngine (default arguments), and RegionStore (global constants). The
former special-cased several kinds of simple constant expressions, while
the latter two deferred to the AST's constant evaluator.
Now, these are all unified as SValBuilder::getConstantVal(). To keep
Environment fast, the special cases for simple constant expressions have
been left in, but the main benefits are that (a) unusual constants like
ObjCStringLiterals now work as default arguments and global constant
initializers, and (b) we're not duplicating code between ExprEngine and
RegionStore.
This actually caught a bug in our test suite, which is awesome: we stop
tracking allocated memory if it's passed as an argument along with some
kind of callback, but not if the callback is 0. We were testing this in
a case where the callback parameter had a default value, but that value
was 0. After this change, the analyzer now (correctly) flags that as a
leak!
<rdar://problem/13773117>
llvm-svn: 180894
This doesn't appear to be the cause of the slowdown. I'll have to try a
manual bisect to see if there's really anything there, or if it's just
the bot itself taking on additional load. Meanwhile, this change helps
with correctness.
This changes an assertion and adds a test case, then re-applies r180638,
which was reverted in r180714.
<rdar://problem/13296133> and PR15863
llvm-svn: 180864
This seems to be causing quite a slowdown on our internal analyzer bot,
and I'm not sure why. Needs further investigation.
This reverts r180638 / 9e161ea981f22ae017b6af09d660bfc3ddf16a09.
llvm-svn: 180714
Casts to bool (and _Bool) are equivalent to checks against zero,
not truncations to 1 bit or 8 bits.
This improved reasoning does cause a change in the behavior of the alpha
BoolAssignment checker. Previously, this checker complained about statements
like "bool x = y" if 'y' was known not to be 0 or 1. Now it does not, since
that conversion is well-defined. It's hard to say what the "best" behavior
here is: this conversion is safe, but might be better written as an explicit
comparison against zero.
More usefully, besides improving our model of booleans, this fixes spurious
warnings when returning the address of a local variable cast to bool.
<rdar://problem/13296133>
llvm-svn: 180638
When computing the value of ?: expression, we rely on the last expression in
the previous basic block to be the resulting value of the expression. This is
not the case for binary "?:" operator (GNU extension) in C++. As the last
basic block has the expression for the condition subexpression, which is an
R-value, whereas the true subexpression is the L-value.
Note the operator evaluation just happens to work in C since the true
subexpression is an R-value (like the condition subexpression). CFG is the
same in C and C++ case, but the AST nodes are different, which the LValue to
Rvalue conversion happening after the BinaryConditionalOperator evaluation.
Changed the logic to only use the last expression from the predecessor only
if it matches either true or false subexpression. Note, the logic needed
fortification anyway: L and R were passed but not even used by the function.
Also, change the conjureSymbolVal to correctly compute the type, when the
expression is an LG-value.
llvm-svn: 179574
Previously, the analyzer used isIntegerType() everywhere, which uses the C
definition of "integer". The C++ predicate with the same behavior is
isIntegerOrUnscopedEnumerationType().
However, the analyzer is /really/ using this to ask if it's some sort of
"integrally representable" type, i.e. it should include C++11 scoped
enumerations as well. hasIntegerRepresentation() sounds like the right
predicate, but that includes vectors, which the analyzer represents by its
elements.
This commit audits all uses of isIntegerType() and replaces them with the
general isIntegerOrEnumerationType(), except in some specific cases where
it makes sense to exclude scoped enumerations, or any enumerations. These
cases now use isIntegerOrUnscopedEnumerationType() and getAs<BuiltinType>()
plus BuiltinType::isInteger().
isIntegerType() is hereby banned in the analyzer - lib/StaticAnalysis and
include/clang/StaticAnalysis. :-)
Fixes real assertion failures. PR15703 / <rdar://problem/12350701>
llvm-svn: 179081
uncovered.
This required manually correcting all of the incorrect main-module
headers I could find, and running the new llvm/utils/sort_includes.py
script over the files.
I also manually added quite a few missing headers that were uncovered by
shuffling the order or moving headers up to be main-module-headers.
llvm-svn: 169237
No need to have the "get", the word "conjure" is a verb too!
Getting a conjured symbol is the same as conjuring one up.
This shortening is largely cosmetic, but just this simple changed
cleaned up a handful of lines, making them less verbose.
llvm-svn: 162348
Add a concept of symbolic memory region belonging to heap memory space.
When comparing symbolic regions allocated on the heap, assume that they
do not alias.
Use symbolic heap region to suppress a common false positive pattern in
the malloc checker, in code that relies on malloc not returning the
memory aliased to other malloc allocations, stack.
llvm-svn: 158136
The resulting type info is stored in the SymSymExpr, so no reason not to
support construction of expression with different subexpression types.
llvm-svn: 156051
The change resulted in multiple issues on the buildbot, so it's not
ready for prime time. Only enable history tracking for tainted
data(which is experimental) for now.
llvm-svn: 156049
reason about the expression.
This essentially keeps more history about how symbolic values were
constructed. As an optimization, previous to this commit, we only kept
the history if one of the symbols was tainted, but it's valuable keep
the history around for other purposes as well: it allows us to avoid
constructing conjured symbols.
Specifically, we need to identify the value of ptr as
ElementRegion (result of pointer arithmetic) in the following code.
However, before this commit '(2-x)' evaluated to Unknown value, and as
the result, 'p + (2-x)' evaluated to Unknown value as well.
int *p = malloc(sizeof(int));
ptr = p + (2-x);
This change brings 2% slowdown on sqlite. Fixes radar://11329382.
llvm-svn: 155944
as aborted, but didn't treat such cases as sinks in the ExplodedGraph.
Along the way, add basic support for CXXCatchStmt, expanding the set of code we actually analyze (hopefully correctly).
Fixes: <rdar://problem/10892489>
llvm-svn: 152468
At this point this is largely cosmetic, but it opens the door to replace
ProgramStateRef with a smart pointer that more eagerly acts in the role
of reclaiming unused ProgramState objects.
llvm-svn: 149081
We are now often generating expressions even if the solver is not known to be able to simplify it. This is another cleanup of the existing code, where the rest of the analyzer and checkers should not base their logic on knowing ahead of the time what the solver can reason about.
In this case, CStringChecker is performing a check for overflow of 'left+right' operation. The overflow can be checked with either 'maxVal-left' or 'maxVal-right'. Previously, the decision was based on whether the expresion evaluated to undef or not. With this patch, we check if one of the arguments is a constant, in which case we know that 'maxVal-const' is easily simplified. (Another option is to use canReasonAbout() method of the solver here, however, it's currently is protected.)
This patch also contains 2 small bug fixes:
- swap the order of operators inside SValBuilder::makeGenericVal.
- handle a case when AddeVal is unknown in GenericTaintChecker::getPointedToSymbol.
llvm-svn: 146343
Fix a bug in SimpleSValBuilder, where we should swap lhs and rhs when calling generateUnknownVal(), - the function which creates symbolic expressions when data is tainted. The issue is not visible when we only create the expressions for taint since all expressions are commutative from taint perspective.
Refactor SymExpr::symbol_iterator::expand() to use a switch instead of a chain of ifs.
llvm-svn: 146336
types are equivalent.
+ A taint test which tests bitwise operations and which was
triggering an assertion due to presence of the integer to integer cast.
llvm-svn: 146240
- Created a new SymExpr type - SymbolCast.
- SymbolCast is created when we don't know how to simplify a NonLoc to
NonLoc casts.
- A bit of code refactoring: introduced dispatchCast to have better
code reuse, remove a goto.
- Updated the test case to showcase the new taint flow.
llvm-svn: 145985
class.
We are going into the direction of handling SymbolData and other SymExpr
uniformly, so it makes less sense to keep two different SVal classes.
For example, the checkers would have to take an extra step to reason
about each type separately.
The classes have the same members, we were just using the SVal kind
field for easy differentiation in 3 switch statements. The switch
statements look more ugly now, but we can make the code more readable in
other ways, for example, moving some code into separate functions.
llvm-svn: 145833
When the solver and SValBuilder cannot reason about symbolic expressions (ex: (x+1)*y ), the analyzer conjures a new symbol with no ties to the past. This helps it to recover some path-sensitivity. However, this breaks the taint propagation.
With this commit, we are going to construct the expression even if we cannot reason about it later on if an operand is tainted.
Also added some comments and asserts.
llvm-svn: 144932
- renames evalCastNL and evalCastL to evalCastFromNonLoc and
evalCastFromLoc (avoid abbreviations that aren't well known).
- makes all function parameter names start with a lower case letter
for consistency and distinction from member variables.
- avoids abbreviations in function parameter names.
Reviewed by kremenek@apple.com.
llvm-svn: 126722
Anna Zaks