New rules of invalidation/escape of the source buffer of memcpy: the source buffer contents is invalidated and escape while the source buffer region itself is neither invalidated, nor escape.
In the current modeling of memcpy the information about allocation state of regions, accessible through the source buffer, is not copied to the destination buffer and we can not track the allocation state of those regions anymore. So we invalidate/escape the source buffer indirect regions in anticipation of their being invalidated for real later. This eliminates false-positive leaks reported by the unix.Malloc and alpha.cplusplus.NewDeleteLeaks checkers for the cases like
char *f() {
void *x = malloc(47);
char *a;
memcpy(&a, &x, sizeof a);
return a;
}
llvm-svn: 194953
This is similar to r194004: because we can't reason about the data structure
invariants of std::basic_string, the analyzer decides it's possible for an
allocator to be used to deallocate the string's inline storage. Just ignore
this by walking up the stack, skipping past methods in classes with
"allocator" in the name, and seeing if we reach std::basic_string that way.
PR17866
llvm-svn: 194764
This syntactic checker looks for expressions on both sides of comparison
operators that are structurally the same. As a special case, the
floating-point idiom "x != x" for "isnan(x)" is left alone.
Currently this only checks comparison operators, but in the future we could
extend this to include logical operators or chained if-conditionals.
Checker by Per Viberg!
llvm-svn: 194236
An Objective-C for-in loop will have zero iterations if the collection is
empty. Previously, we could only detect this case if the program asked for
the collection's -count /before/ the for-in loop. Now, the analyzer
distinguishes for-in loops that had zero iterations from those with at
least one, and can use this information to constrain the result of calling
-count after the loop.
In order to make this actually useful, teach the checker that methods on
NSArray, NSDictionary, and the other immutable collection classes don't
change the count.
<rdar://problem/14992886>
llvm-svn: 194235
The path note that says "Loop body executed 0 times" has been changed to
"Loop body skipped when range is empty" for C++11 for-range loops, and to
"Loop body skipped when collection is empty" for Objective-C for-in loops.
Part of <rdar://problem/14992886>
llvm-svn: 194234
We could certainly be more precise in many of our diagnostics, but before we
were printing "Assuming x is && y", which is just ridiculous.
<rdar://problem/15167979>
llvm-svn: 193455
This ensures that variables accessible through a union are invalidated when
the union value is passed to a function. We still don't fully handle union
values, but this should at least quiet some false positives.
PR16596
llvm-svn: 193265
This patch wasn't reviewed, and isn't correctly preserving the behaviors
relied upon by QT. I don't have a direct example of fallout, but it
should go through the standard code review process. For example, it
should never have removed the QT test case that was added when fixing
those users.
llvm-svn: 193174
Due to statement expressions supported as GCC extension, it is possible
to put 'break' or 'continue' into a loop/switch statement but outside its
body, for example:
for ( ; ({ if (first) { first = 0; continue; } 0; }); )
Such usage must be diagnosed as an error, GCC rejects it. To recognize
this and similar patterns the flags BreakScope and ContinueScope are
temporarily turned off while parsing condition expression.
Differential Revision: http://llvm-reviews.chandlerc.com/D1762
llvm-svn: 193073
Since these aren't lexically in the constructor, drawing arrows would
be a horrible jump across the body of the class. We could still do
better here by skipping over unimportant initializers, but this at least
keeps everything within the body of the constructor.
<rdar://problem/14960554>
llvm-svn: 192818
This will emit a warning if a call to clang_analyzer_warnIfReached is
executed, printing REACHABLE. This is a more explicit way to declare
expected reachability than using clang_analyzer_eval or triggering
a bug (divide-by-zero or null dereference), and unlike the former will
work the same in inlined functions and top-level functions. Like the
other debug helpers, it is part of the debug.ExprInspection checker.
Patch by Jared Grubb!
llvm-svn: 191909
Also add some tests that there is actually a message and that the bug is
actually a hard error. This actually behaved correctly before, because:
- addTransition() doesn't actually add a transition if the new state is null;
it assumes you want to propagate the predecessor forward and does nothing.
- generateSink() is called in order to emit a bug report.
- If at least one new node has been generated, the predecessor node is /not/
propagated forward.
But now it's spelled out explicitly.
Found by Richard Mazorodze, who's working on a patch that may require this.
llvm-svn: 191805
...rather than trying to figure it out from the call site, and having
people complain that we guessed wrong and that a prototype-less call is
the same as a variadic call on their system. More importantly, fix a
crash when there's no decl at the call site (though we could have just
returned a default value).
<rdar://problem/15037033>
llvm-svn: 191599
Now that the CFG includes nodes for the destructors in a delete-expression,
process them in the analyzer using the same common destructor interface
currently used for local, member, and base destructors. Also, check for when
the value is known to be null, in which case no destructor is actually run.
This does not yet handle destructors for deleted /arrays/, which may need
more CFG work. It also causes a slight regression in the location of
double delete warnings; the double delete is detected at the destructor
call, which is implicit, and so is reported on the first access within the
destructor instead of at the 'delete' statement. This will be fixed soon.
Patch by Karthik Bhat!
llvm-svn: 191381
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
"+method_name: cannot take ownership of memory allocated by 'new'."
instead of the old
"Memory allocated by 'new' should be deallocated by 'delete', not +method_name"
llvm-svn: 190800
variable uninitialized every time we reach its (reachable) declaration, or
every time we call the surrounding function, promote the warning from
-Wmaybe-uninitialized to -Wsometimes-uninitialized.
This is still slightly weaker than desired: we should, in general, warn
if a use is uninitialized the first time it is evaluated.
llvm-svn: 190623
RegionStore tries to protect against accidentally initializing the same
region twice, but it doesn't take subregions into account very well. If
the outer region being initialized is a struct with an empty base class,
the offset of the first field in the struct will be 0. When we initialize
the base class, we may invalidate the contents of the struct by providing
a default value of Unknown (or some new symbol). We then go to initialize
the member with a zeroing constructor, only to find that the region at
that offset in the struct already has a value. The best we can do here is
to invalidate that value and continue; neither the old default value nor
the new 0 is correct for the entire struct after the member constructor call.
The correct solution for this is to track region extents in the store.
<rdar://problem/14914316>
llvm-svn: 190530
Summary:
If a noreturn destructor is executed while returning a value from a function,
the resulting CFG has had two edges to the exit block. This crashed the analyzer,
because it expects that blocks with no terminators have only one outgoing edge.
I added code to avoid creating the second edge in this case.
PS: The crashes did not manifest themselves always, as usually the
NoReturnFunctionChecker would stop program evaluation before the analyzer hit
the assertion, but in the case of lifetime extended temporaries, the checker
failed to do that (which is a separate bug in itself).
Reviewers: jordan_rose
CC: cfe-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D1513
llvm-svn: 190125
Summary:
I've had a test failure here while experimenting and I've found that it's
impossible to find what is wrong with the previous structure of the file. So I
have grouped the expected output with the function that produces it, to make
searching for discrepancies more obvious.
Reviewers: jordan_rose
CC: cfe-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D1595
llvm-svn: 190037
This paves the way for adding support for modeling the destructor of a
region before it is deleted. The statement "delete <expr>" now generates
this series of CFG elements:
1. <expr>
2. [B1.1]->~Foo() (Implicit destructor)
3. delete [B1.1]
Patch by Karthik Bhat!
llvm-svn: 189828
This is an improved version of r186498. It enables ExprEngine to reason about
temporary object destructors. However, these destructor calls are never
inlined, since this feature is still broken. Still, this is sufficient to
properly handle noreturn temporary destructors.
Now, the analyzer correctly handles expressions like "a || A()", and executes the
destructor of "A" only on the paths where "a" evaluted to false.
Temporary destructor processing is still off by default and one has to
explicitly request it by setting cfg-temporary-dtors=true.
Reviewers: jordan_rose
CC: cfe-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D1259
llvm-svn: 189746
This will never happen in the analyzed code code, but can happen for checkers
that over-eagerly dereference pointers without checking that it's safe.
UnknownVal is a harmless enough value to get back.
Fixes an issue added in r189590, caught by our internal buildbot.
llvm-svn: 189688
Summary:
Previously, Sema was reusing parts of the AST when synthesizing an assignment
operator, turning it into a AS-dag. This caused problems for the static
analyzer, which assumed an expression appears in the tree only once.
Here I make sure to always create a fresh Expr, when inserting something into
the AST, fixing PR16745 in the process.
Reviewers: doug.gregor
CC: cfe-commits, jordan_rose
Differential Revision: http://llvm-reviews.chandlerc.com/D1425
llvm-svn: 189659
Summary:
RegionStoreManager had an optimization which replaces references to empty
structs with UnknownVal. Unfortunately, this check didn't take into account
possible field members in base classes.
To address this, I changed this test to "is empty and has no base classes". I
don't consider it worth the trouble to go through base classes and check if all
of them are empty.
Reviewers: jordan_rose
CC: cfe-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D1547
llvm-svn: 189590
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
Summary:
-fno-exceptions does not implicitly attach a nothrow specifier to every operator
new. Even in this mode, non-nothrow new must not return a null pointer. Failure
to allocate memory can be signalled by other means, or just by killing the
program. This behaviour is consistent with the compiler - even with
-fno-exceptions, the generated code never tests for null (and would segfault if
the opeator actually happened to return null).
Reviewers: jordan_rose
CC: cfe-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D1528
llvm-svn: 189452
Summary:
Instead of digging through the ExplodedGraph, to figure out which edge brought
us here, I compute the value of conditional expression by looking at the
sub-expression values.
To do this, I needed to change the liveness algorithm a bit -- now, the full
conditional expression also depends on all atomic sub-expressions, not only the
outermost ones.
Reviewers: jordan_rose
CC: cfe-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D1340
llvm-svn: 189090
This is still an alpha checker, but we use it in certain tests to make sure
something is not being executed.
This should fix the buildbots.
llvm-svn: 188682
This keeps the analyzer from making silly assumptions, like thinking
strlen(foo)+1 could wrap around to 0. This fixes PR16558.
Patch by Karthik Bhat!
llvm-svn: 188680
This builtin does not actually evaluate its arguments for side effects,
so we shouldn't include them in the CFG. In the analyzer, rely on the
constant expression evaluator to get the proper semantics, at least for
now. (In the future, we could get ambitious and try to provide path-
sensitive size values.)
In theory, this does pose a problem for liveness analysis: a variable can
be used within the __builtin_object_size argument expression but not show
up as live. However, it is very unlikely that such a value would be used
to compute the object size and not used to access the object in some way.
<rdar://problem/14760817>
llvm-svn: 188679
This once again restores notes to following their associated warnings
in -analyzer-output=text mode. (This is still only intended for use as a
debugging aid.)
One twist is that the warning locations in "regular" analysis output modes
(plist, multi-file-plist, html, and plist-html) are reported at a different
location on the command line than in the output file, since the command
line has no path context. This commit makes -analyzer-output=text behave
like a normal output format, which means that the *command line output
will be different* in -analyzer-text mode. Again, since -analyzer-text is
a debugging aid and lo-fi stand-in for a regular output mode, this change
makes sense.
Along the way, remove a few pieces of stale code related to the path
diagnostic consumers.
llvm-svn: 188514
When a region is realloc()ed, MallocChecker records whether it was known
to be allocated or not. If it is, and the reallocation fails, the original
region has to be freed. Previously, when an allocated region escaped,
MallocChecker completely stopped tracking it, so a failed reallocation
still (correctly) wouldn't require freeing the original region. Recently,
however, MallocChecker started tracking escaped symbols, so that if it were
freed we could check that the deallocator matched the allocator. This
broke the reallocation model for whether or not a symbol was allocated.
Now, MallocChecker will actually check if a symbol is owned, and only
require freeing after a failed reallocation if it was owned before.
PR16730
llvm-svn: 188468
Various tests had sprung up over the years which had --check-prefix=ABC on the
RUN line, but "CHECK-ABC:" later on. This happened to work before, but was
strictly incorrect. FileCheck is getting stricter soon though.
Patch by Ron Ofir.
llvm-svn: 188174
Anna Zaks