[compiler-rt] r302152 - [ASAN] Add interceptor for __longjmp_chk

[Peter Wu via llvm-commits]

Author: lekensteyn
Date: Thu May  4 09:03:57 2017
New Revision: 302152

URL: http://llvm.org/viewvc/llvm-project?rev=302152&view=rev
Log:
[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

Added:
    compiler-rt/trunk/test/asan/TestCases/Linux/longjmp_chk.c   (with props)
Modified:
    compiler-rt/trunk/lib/asan/asan_interceptors.cc
    compiler-rt/trunk/lib/asan/asan_interceptors.h

Modified: compiler-rt/trunk/lib/asan/asan_interceptors.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_interceptors.cc?rev=302152&r1=302151&r2=302152&view=diff
==============================================================================
--- compiler-rt/trunk/lib/asan/asan_interceptors.cc (original)
+++ compiler-rt/trunk/lib/asan/asan_interceptors.cc Thu May  4 09:03:57 2017
@@ -443,6 +443,13 @@ INTERCEPTOR(void, _longjmp, void *env, i
 }
 #endif
 
+#if ASAN_INTERCEPT___LONGJMP_CHK
+INTERCEPTOR(void, __longjmp_chk, void *env, int val) {
+  __asan_handle_no_return();
+  REAL(__longjmp_chk)(env, val);
+}
+#endif
+
 #if ASAN_INTERCEPT_SIGLONGJMP
 INTERCEPTOR(void, siglongjmp, void *env, int val) {
   __asan_handle_no_return();
@@ -758,6 +765,9 @@ void InitializeAsanInterceptors() {
 #if ASAN_INTERCEPT__LONGJMP
   ASAN_INTERCEPT_FUNC(_longjmp);
 #endif
+#if ASAN_INTERCEPT___LONGJMP_CHK
+  ASAN_INTERCEPT_FUNC(__longjmp_chk);
+#endif
 #if ASAN_INTERCEPT_SIGLONGJMP
   ASAN_INTERCEPT_FUNC(siglongjmp);
 #endif

Modified: compiler-rt/trunk/lib/asan/asan_interceptors.h
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_interceptors.h?rev=302152&r1=302151&r2=302152&view=diff
==============================================================================
--- compiler-rt/trunk/lib/asan/asan_interceptors.h (original)
+++ compiler-rt/trunk/lib/asan/asan_interceptors.h Thu May  4 09:03:57 2017
@@ -58,6 +58,12 @@
 # define ASAN_INTERCEPT_SIGLONGJMP 0
 #endif
 
+#if SANITIZER_LINUX && !SANITIZER_ANDROID
+# define ASAN_INTERCEPT___LONGJMP_CHK 1
+#else
+# define ASAN_INTERCEPT___LONGJMP_CHK 0
+#endif
+
 // Android bug: https://code.google.com/p/android/issues/detail?id=61799
 #if ASAN_HAS_EXCEPTIONS && !SANITIZER_WINDOWS && \
     !(SANITIZER_ANDROID && defined(__i386))

Added: compiler-rt/trunk/test/asan/TestCases/Linux/longjmp_chk.c
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/asan/TestCases/Linux/longjmp_chk.c?rev=302152&view=auto
==============================================================================
--- compiler-rt/trunk/test/asan/TestCases/Linux/longjmp_chk.c (added)
+++ compiler-rt/trunk/test/asan/TestCases/Linux/longjmp_chk.c Thu May  4 09:03:57 2017
@@ -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

Propchange: compiler-rt/trunk/test/asan/TestCases/Linux/longjmp_chk.c
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