[ASAN] Add interceptor for __longjmp_chk

Summary:
glibc on Linux calls __longjmp_chk instead of longjmp (or _longjmp) when
_FORTIFY_SOURCE is defined. Ensure that an ASAN-instrumented program
intercepts this function when a system library calls it, otherwise the
stack might remain poisoned and result in CHECK failures and false
positives.

Fixes https://github.com/google/sanitizers/issues/721

Reviewed By: eugenis

Differential Revision: https://reviews.llvm.org/D32408

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@302152 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 51 insertions, 0 deletions

diff --git a/test/asan/TestCases/Linux/longjmp_chk.c b/test/asan/TestCases/Linux/longjmp_chk.c
new file mode 100644
index 000000000..99a4a1630
--- /dev/null
+++ b/test/asan/TestCases/Linux/longjmp_chk.c
@@ -0,0 +1,51 @@
+// Verify that use of longjmp() in a _FORTIFY_SOURCE'd library (without ASAN)
+// is correctly intercepted such that the stack is unpoisoned.
+// Note: it is essential that the external library is not built with ASAN,
+// otherwise it would be able to unpoison the stack before use.
+//
+// RUN: %clang -DIS_LIBRARY -D_FORTIFY_SOURCE=2 -O2 %s -c -o %t.o
+// RUN: %clang_asan -O2 %s %t.o -o %t
+// RUN: %run %t
+
+#ifdef IS_LIBRARY
+/* the library */
+#include <setjmp.h>
+#include <assert.h>
+#include <sanitizer/asan_interface.h>
+
+static jmp_buf jenv;
+
+void external_callme(void (*callback)(void)) {
+  if (setjmp(jenv) == 0) {
+    callback();
+  }
+}
+
+void external_longjmp(char *msg) {
+  longjmp(jenv, 1);
+}
+
+void external_check_stack(void) {
+  char buf[256] = "";
+  for (int i = 0; i < 256; i++) {
+    assert(!__asan_address_is_poisoned(buf + i));
+  }
+}
+#else
+/* main program */
+extern void external_callme(void (*callback)(void));
+extern void external_longjmp(char *msg);
+extern void external_check_stack(void);
+
+static void callback(void) {
+  char msg[16];   /* Note: this triggers addition of a redzone. */
+  /* Note: msg is passed to prevent compiler optimization from removing it. */
+  external_longjmp(msg);
+}
+
+int main() {
+  external_callme(callback);
+  external_check_stack();
+  return 0;
+}
+#endif