[Static Analyzer] BugReporter.cpp:2869: Assertion failed: !RemainingNodes.empty(...

The assertion is caused by reusing a “filler” ExplodedNode as an error node.
The “filler” nodes are only used for intermediate processing and are not
essential for analyzer history, so they can be reclaimed when the
ExplodedGraph is trimmed by the “collectNode” function. When a checker finds a
bug, they generate a new transition in the ExplodedGraph. The analyzer will
try to reuse the existing predecessor node. If it cannot, it creates a new
ExplodedNode, which always has a tag to uniquely identify the creation site.
The assertion is caused when the analyzer reuses a “filler” node.

In the test case, some “filler” nodes were reused and then reclaimed later
when the ExplodedGraph was trimmed. This caused an assertion because the node
was needed to generate the report. The “filler” nodes should not be reused as
error nodes. The patch adds a constraint to prevent this happening, which
solves the problem and makes the test cases pass.

Differential Revision: http://reviews.llvm.org/D11433

Patch by Ying Yi!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@246188 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h b/include/clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h
index a4ff133b4b93208afff354c2d900ad64d54b5e2c..e72a1924bce6fcc261523c24c12c2c150c5f830b 100644 (file)
--- a/include/clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h
+++ b/include/clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h
@@ -287,7 +287,10 @@ private:
                                  bool MarkAsSink,
                                  ExplodedNode *P = nullptr,
                                  const ProgramPointTag *Tag = nullptr) {
-    if (!State || (State == Pred->getState() && !Tag && !MarkAsSink))
+    // It may not be safe to use the "Pred" node with no tag because the "Pred"
+    // node may be recycled in the reclamation function.
+    if (!State || (State == Pred->getState() && !Tag && !MarkAsSink &&
+                   Pred->getLocation().getTag()))
       return Pred;
 
     Changed = true;

diff --git a/test/Analysis/PR24184.cpp b/test/Analysis/PR24184.cpp
new file mode 100644 (file)
index 0000000..e495211
--- /dev/null
+++ b/test/Analysis/PR24184.cpp
@@ -0,0 +1,97 @@
+// RUN: %clang_cc1 -w -analyze -analyzer-eagerly-assume -fcxx-exceptions -analyzer-checker=core -analyzer-checker=alpha.core.PointerArithm,alpha.core.CastToStruct -analyzer-max-loop 64 -verify %s
+// RUN: %clang_cc1 -w -analyze -analyzer-checker=core -analyzer-checker=cplusplus -fcxx-exceptions -analyzer-checker alpha.core.PointerArithm,alpha.core.CastToStruct -analyzer-max-loop 63 -verify %s
+
+// These tests used to hit an assertion in the bug report. Test case from http://llvm.org/PR24184.
+typedef struct {
+  int cbData;
+  unsigned pbData;
+} CRYPT_DATA_BLOB;
+
+typedef enum { DT_NONCE_FIXED } DATA_TYPE;
+int a;
+typedef int *vcreate_t(int *, DATA_TYPE, int, int);
+void fn1(unsigned, unsigned) {
+  char b = 0;
+  for (; 1; a++, &b + a * 0) // expected-warning{{Pointer arithmetic done on non-array variables means reliance on memory layout, which is dangerous}}
+    ;
+}
+
+vcreate_t fn2;
+struct A {
+  CRYPT_DATA_BLOB value;
+  int m_fn1() {
+    int c;
+    value.pbData == 0;
+    fn1(0, 0);
+  }
+};
+struct B {
+  A IkeHashAlg;
+  A IkeGType;
+  A NoncePhase1_r;
+};
+class C {
+  int m_fn2(B *);
+  void m_fn3(B *, int, int, int);
+};
+int C::m_fn2(B *p1) {
+  int *d;
+  int e = p1->IkeHashAlg.m_fn1();
+  unsigned f = p1->IkeGType.m_fn1(), h;
+  int g;
+  d = fn2(0, DT_NONCE_FIXED, (char)0, p1->NoncePhase1_r.value.cbData);
+  h = 0 | 0;
+  m_fn3(p1, 0, 0, 0);
+}
+
+// case 2:
+typedef struct {
+  int cbData;
+  unsigned char *pbData;
+} CRYPT_DATA_BLOB_1;
+typedef unsigned uint32_t;
+void fn1_1(void *p1, const void *p2) { p1 != p2; }
+
+void fn2_1(uint32_t *p1, unsigned char *p2, uint32_t p3) {
+  unsigned i = 0;
+  for (0; i < p3; i++)
+    fn1_1(p1 + i, p2 + i * 0);    // expected-warning{{Pointer arithmetic done on non-array variables means reliance on memory layout, which is dangerous}}
+}
+
+struct A_1 {
+  CRYPT_DATA_BLOB_1 value;
+  uint32_t m_fn1() {
+    uint32_t a;
+    if (value.pbData)
+      fn2_1(&a, value.pbData, value.cbData);
+    return 0;
+  }
+};
+struct {
+  A_1 HashAlgId;
+} *b;
+void fn3() {
+  uint32_t c, d;
+  d = b->HashAlgId.m_fn1();
+  d << 0 | 0 | 0;
+  c = 0;
+  0 | 1 << 0 | 0 && b;
+}
+
+// case 3:
+struct ST {
+  char c;
+};
+char *p;
+int foo1(ST);
+int foo2() {
+  ST *p1 = (ST *)(p);      // expected-warning{{Casting a non-structure type to a structure type and accessing a field can lead to memory access errors or data corruption}}
+  while (p1->c & 0x0F || p1->c & 0x07)
+    p1 = p1 + foo1(*p1);
+}
+
+int foo3(int *node) {
+  int i = foo2();
+  if (i)
+    return foo2();
+}
\ No newline at end of file

diff --git a/test/Analysis/malloc.c b/test/Analysis/malloc.c
index 662df4c28b7752bfdcca99250e873612f1701e42..5ea4f008f45857f43f2a450f162a40c5a175bfab 100644 (file)
--- a/test/Analysis/malloc.c
+++ b/test/Analysis/malloc.c
@@ -1386,7 +1386,8 @@ char* reallocButNoMalloc(struct HasPtr *a, int c, int size) {
   int *s;
   char *b = realloc(a->p, size);
   char *m = realloc(a->p, size); // expected-warning {{Attempt to free released memory}}
-  return a->p;
+  //PR24184: Object "a->p" is returned after being freed by calling "realloc".
+  return a->p; // expected-warning {{Use of memory after it is freed}}
 }
 
 // We should not warn in this case since the caller will presumably free a->p in all cases.