Summary:
The kernel kmalloc function may return a constant value ZERO_SIZE_PTR
if a zero-sized block is allocated. This special value is allowed to
be passed to kfree and should produce no warning.
This is a simple version but should be no problem. The macro is always
detected independent of if this is a kernel source code or any other
code.
Reviewers: Szelethus, martong
Reviewed By: Szelethus, martong
Subscribers: rnkovacs, xazax.hun, baloghadamsoftware, szepet, a.sidorin, mikhail.ramalho, Szelethus, donat.nagy, dkrupp, gamesh411, Charusso, martong, ASDenysPetrov, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D76830
Writing stuff into an argument variable is usually equivalent to writing stuff
to a local variable: it will have no effect outside of the function.
There's an important exception from this rule: if the argument variable has
a non-trivial destructor, the destructor would be invoked on
the parent stack frame, exposing contents of the otherwise dead
argument variable to the caller.
If such argument is the last place where a pointer is stored before the function
exits and the function is the one we've started our analysis from (i.e., we have
no caller context for it), we currently diagnose a leak. This is incorrect
because the destructor of the argument still has access to the pointer.
The destructor may deallocate the pointer or even pass it further.
Treat writes into such argument regions as "escapes" instead, suppressing
spurious memory leak reports but not messing with dead symbol removal.
Differential Revision: https://reviews.llvm.org/D60112
llvm-svn: 358321
In order to provide more test coverage for inlined operator new(), add more
run-lines to existing test cases, which would trigger our fake header
to provide a body for operator new(). Most of the code should still behave
reasonably. When behavior intentionally changes, #ifs are provided.
Differential Revision: https://reviews.llvm.org/D42221
llvm-svn: 323376
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
Refactor invalidateRegions to take SVals instead of Regions as input and teach RegionStore
about processing LazyCompoundVal as a top-level “escaping” value.
This addresses several false positives that get triggered by the NewDelete checker, but the
underlying issue is reproducible with other checkers as well (for example, MallocChecker).
llvm-svn: 178518
This is a "quick fix".
The underlining issue is that when a const pointer to a struct is passed
into a function, we do not invalidate the pointer fields. This results
in false positives that are common in C++ (since copy constructors are
prevalent). (Silences two llvm false positives.)
llvm-svn: 174468
This fixes a few cases where we'd emit path notes like this:
+---+
1| v
p = malloc(len);
^ |2
+---+
In general this should make path notes more consistent and more correct,
especially in cases where the leak happens on the false branch of an if
that jumps directly to the end of the function. There are a couple places
where the leak is reported farther away from the cause; these are usually
cases where there are several levels of nested braces before the end of
the function. This still matches our current behavior for when there /is/
a statement after all the braces, though.
llvm-svn: 168070
While destructors will continue to not be inlined (unless the analyzer
config option 'c++-inlining' is set to 'destructors'), leaving them out
of the CFG is an incomplete model of the behavior of an object, and
can cause false positive warnings (like PR13751, now working).
Destructors for temporaries are still not on by default, since
(a) we haven't actually checked this code to be sure it's fully correct
(in particular, we probably need to be very careful with regard to
lifetime-extension when a temporary is bound to a reference,
C++11 [class.temporary]p5), and
(b) ExprEngine doesn't actually do anything when it sees a temporary
destructor in the CFG -- not even invalidate the object region.
To enable temporary destructors, set the 'cfg-temporary-dtors' analyzer
config option to '1'. The old -cfg-add-implicit-dtors cc1 option, which
controlled all implicit destructors, has been removed.
llvm-svn: 163264
Balázs Kéri