r289886 - [analyzer] Teach the analyzer that pointers can escape into __cxa_demangle
Anna Zaks via cfe-commits
cfe-commits at lists.llvm.org
Thu Dec 15 14:55:19 PST 2016
Author: zaks
Date: Thu Dec 15 16:55:18 2016
New Revision: 289886
URL: http://llvm.org/viewvc/llvm-project?rev=289886&view=rev
Log:
[analyzer] Teach the analyzer that pointers can escape into __cxa_demangle
This fixes a reported false positive in the malloc checker.
Differential Revision: https://reviews.llvm.org/D27599
Modified:
cfe/trunk/lib/StaticAnalyzer/Core/CallEvent.cpp
cfe/trunk/test/Analysis/Inputs/system-header-simulator-cxx.h
cfe/trunk/test/Analysis/malloc.cpp
Modified: cfe/trunk/lib/StaticAnalyzer/Core/CallEvent.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/StaticAnalyzer/Core/CallEvent.cpp?rev=289886&r1=289885&r2=289886&view=diff
==============================================================================
--- cfe/trunk/lib/StaticAnalyzer/Core/CallEvent.cpp (original)
+++ cfe/trunk/lib/StaticAnalyzer/Core/CallEvent.cpp Thu Dec 15 16:55:18 2016
@@ -382,6 +382,11 @@ bool AnyFunctionCall::argumentsMayEscape
if (II->isStr("funopen"))
return true;
+ // - __cxa_demangle - can reallocate memory and can return the pointer to
+ // the input buffer.
+ if (II->isStr("__cxa_demangle"))
+ return true;
+
StringRef FName = II->getName();
// - CoreFoundation functions that end with "NoCopy" can free a passed-in
Modified: cfe/trunk/test/Analysis/Inputs/system-header-simulator-cxx.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Analysis/Inputs/system-header-simulator-cxx.h?rev=289886&r1=289885&r2=289886&view=diff
==============================================================================
--- cfe/trunk/test/Analysis/Inputs/system-header-simulator-cxx.h (original)
+++ cfe/trunk/test/Analysis/Inputs/system-header-simulator-cxx.h Thu Dec 15 16:55:18 2016
@@ -240,3 +240,12 @@ void* operator new (std::size_t size, vo
void* operator new[] (std::size_t size, void* ptr) throw() { return ptr; };
void operator delete (void* ptr, void*) throw() {};
void operator delete[] (void* ptr, void*) throw() {};
+
+namespace __cxxabiv1 {
+extern "C" {
+extern char *__cxa_demangle(const char *mangled_name,
+ char *output_buffer,
+ size_t *length,
+ int *status);
+}}
+namespace abi = __cxxabiv1;
Modified: cfe/trunk/test/Analysis/malloc.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Analysis/malloc.cpp?rev=289886&r1=289885&r2=289886&view=diff
==============================================================================
--- cfe/trunk/test/Analysis/malloc.cpp (original)
+++ cfe/trunk/test/Analysis/malloc.cpp Thu Dec 15 16:55:18 2016
@@ -1,6 +1,8 @@
// RUN: %clang_cc1 -w -analyze -analyzer-checker=core,alpha.deadcode.UnreachableCode,alpha.core.CastSize,unix.Malloc,cplusplus.NewDelete -analyzer-store=region -verify %s
// RUN: %clang_cc1 -triple i386-unknown-linux-gnu -w -analyze -analyzer-checker=core,alpha.deadcode.UnreachableCode,alpha.core.CastSize,unix.Malloc,cplusplus.NewDelete -analyzer-store=region -verify %s
+#include "Inputs/system-header-simulator-cxx.h"
+
typedef __typeof(sizeof(int)) size_t;
void *malloc(size_t);
void free(void *);
@@ -125,3 +127,15 @@ namespace PR31226 {
p->m(); // no-crash // no-warning
}
}
+
+// Allow __cxa_demangle to escape.
+char* test_cxa_demangle(const char* sym) {
+ size_t funcnamesize = 256;
+ char* funcname = (char*)malloc(funcnamesize);
+ int status;
+ char* ret = abi::__cxa_demangle(sym, funcname, &funcnamesize, &status);
+ if (status == 0) {
+ funcname = ret;
+ }
+ return funcname; // no-warning
+}
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