[lsan] Fix bug when discovering indirectly leaked objects.

If an object contains pointers to itself, that doesn't make it indirectly
leaked. D'oh!

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@192716 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 20 insertions, 0 deletions

diff --git a/lib/lsan/lit_tests/TestCases/pointer_to_self.cc b/lib/lsan/lit_tests/TestCases/pointer_to_self.cc
new file mode 100644
index 00000000..ecfe11b7
--- /dev/null
+++ b/lib/lsan/lit_tests/TestCases/pointer_to_self.cc
@@ -0,0 +1,18 @@
+// Regression test: pointers to self should not confuse LSan into thinking the
+// object is indirectly leaked. Only external pointers count.
+// RUN: LSAN_BASE="report_objects=1:use_registers=0"
+// RUN: %clangxx_lsan %s -o %t
+// RUN: LSAN_OPTIONS=$LSAN_BASE:"use_stacks=0" not %t 2>&1 | FileCheck %s
+
+#include <stdio.h>
+#include <stdlib.h>
+
+int main() {
+  void *p = malloc(1337);
+  *reinterpret_cast<void **>(p) = p;
+  fprintf(stderr, "Test alloc: %p.\n", p);
+}
+// CHECK: Test alloc: [[ADDR:.*]].
+// CHECK: Directly leaked 1337 byte object at [[ADDR]]
+// CHECK: LeakSanitizer: detected memory leaks
+// CHECK: SUMMARY: LeakSanitizer:
diff --git a/lib/lsan/lsan_common.cc b/lib/lsan/lsan_common.cc
index a58e604f..ec914979 100644
--- a/lib/lsan/lsan_common.cc
+++ b/lib/lsan/lsan_common.cc
@@ -138,6 +138,8 @@ void ScanRangeForPointers(uptr begin, uptr end,
     if (!CanBeAHeapPointer(reinterpret_cast<uptr>(p))) continue;
     uptr chunk = PointsIntoChunk(p);
     if (!chunk) continue;
+    // Pointers to self don't count. This matters when tag == kIndirectlyLeaked.
+    if (chunk == begin) continue;
     LsanMetadata m(chunk);
     // Reachable beats ignored beats leaked.
     if (m.tag() == kReachable) continue;