[sanitizer] Clear LD_PRELOAD when forking an external symbolizer.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@180599 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 20 insertions, 0 deletions

diff --git a/lib/sanitizer_common/sanitizer_common.h b/lib/sanitizer_common/sanitizer_common.h
index 9df510b85..9335ca71a 100644
--- a/lib/sanitizer_common/sanitizer_common.h
+++ b/lib/sanitizer_common/sanitizer_common.h
@@ -131,6 +131,7 @@ void DumpProcessMap();
 bool FileExists(const char *filename);
 const char *GetEnv(const char *name);
 bool SetEnv(const char *name, const char *value);
+void UnsetEnv(const char *name);
 const char *GetPwd();
 u32 GetUid();
 void ReExec();
diff --git a/lib/sanitizer_common/sanitizer_linux.cc b/lib/sanitizer_common/sanitizer_linux.cc
index ef185571a..1c9cbf83a 100644
--- a/lib/sanitizer_common/sanitizer_linux.cc
+++ b/lib/sanitizer_common/sanitizer_linux.cc
@@ -278,6 +278,20 @@ bool SetEnv(const char *name, const char *value) {
 }
 #endif
 
+void UnsetEnv(const char *name) {
+  uptr name_length = internal_strlen(name);
+  uptr last = 0;
+  while (environ[last]) last++;
+  for (uptr i = 0; environ[i]; i++)
+    if (internal_strlen(environ[i]) >= name_length + 1 &&
+        internal_strncmp(environ[i], name, name_length) == 0 &&
+        environ[i][name_length] == '=') {
+      last--;
+      environ[i] = environ[last];
+      environ[last] = 0;
+    }
+}
+
 #ifdef __GLIBC__
 
 extern "C" {
diff --git a/lib/sanitizer_common/sanitizer_symbolizer_linux.cc b/lib/sanitizer_common/sanitizer_symbolizer_linux.cc
index 14a682bd9..5c98e93ac 100644
--- a/lib/sanitizer_common/sanitizer_symbolizer_linux.cc
+++ b/lib/sanitizer_common/sanitizer_symbolizer_linux.cc
@@ -100,6 +100,11 @@ bool StartSymbolizerSubprocess(const char *path_to_symbolizer,
     internal_close(infd[1]);
     for (int fd = getdtablesize(); fd > 2; fd--)
       internal_close(fd);
+    // If the parent tool is used as a preloadable library, do not apply it to
+    // the symbolizer.
+    // FIXME: If LD_PRELOAD contains more than one object, we should keep those
+    // that have nothing to do with us.
+    UnsetEnv("LD_PRELOAD");
     execl(path_to_symbolizer, path_to_symbolizer, (char*)0);
     internal__exit(1);
   }