[MSAN] add dn_expand intercept.

[kda]

Summary

This interceptor only addresses writes to inputs. Reads of inputs are not checked.

[kda]

remove commented out code

[kda]

remove commented out code

[vitalybuka]

compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc

2531

int space?

2534

maybe we should drop COMMON_INTERCEPTOR_READ_RANGE, and just keep only WRITE?

[eugenis]

We should also add -lresolv to tools::linkSanitizerRuntimeDeps if we are now intercepting functions from there.
Libresolv is part of libc.so on android.

[kda]

eliminate read checking

[kda]

eliminate read checking

[kda]

I am aware of this breakage: https://lab.llvm.org/buildbot/#/builders/77/builds/18273

I will push a fix shortly.

[browneee]

In D126851#3556476, @kda wrote:

I am aware of this breakage: https://lab.llvm.org/buildbot/#/builders/77/builds/18273

I will push a fix shortly.

Thanks!

[kda]

committed: 21f2ac9a2f95

compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc

INTERCEPTOR(int, __b64_pton, char const *src, char *target, SIZE_T targsize) {
   void *ctx;
   COMMON_INTERCEPTOR_ENTER(ctx, __b64_pton, src, target, targsize);
   COMMON_INTERCEPTOR_READ_RANGE(ctx, src, internal_strlen(src) + 1);
   int res = REAL(__b64_pton)(src, target, targsize);
   if (res >= 0)
     COMMON_INTERCEPTOR_WRITE_RANGE(ctx, target, res);
   return res;
 }
-#  define INIT___B64_TO                    \
+#define INIT___B64_TO                      \
     COMMON_INTERCEPT_FUNCTION(__b64_ntop); \
     COMMON_INTERCEPT_FUNCTION(__b64_pton);
 #else  // SANITIZER_INTERCEPT___B64_TO
 #define INIT___B64_TO
 #endif  // SANITIZER_INTERCEPT___B64_TO
 
+#if SANITIZER_INTERCEPT___DN_EXPAND
+  INTERCEPTOR(int, __dn_expand, unsigned char const *base,
+              unsigned char const *end, unsigned char const *src, char *dest,
+              SIZE_T space) {
+  void *ctx;
+  COMMON_INTERCEPTOR_ENTER(ctx, __dn_expand, base, end, src, dest, space);
+  COMMON_INTERCEPTOR_READ_RANGE(ctx, src, end - src);
+  int res = REAL(__dn_expand)(base, end, src, dest, space);
+  if (res >= 0)
+    COMMON_INTERCEPTOR_WRITE_RANGE(ctx, dest, res + 1);
+  return res;
+}
+#define INIT___DN_EXPAND                    \
+    COMMON_INTERCEPT_FUNCTION(__dn_expand);
+#else  // SANITIZER_INTERCEPT___DN_EXPAND
+#define INIT___DN_EXPAND
+#endif  // SANITIZER_INTERCEPT___DN_EXPAND
+
 
 #if SANITIZER_INTERCEPT_POSIX_SPAWN
 
 template <class RealSpawnPtr>
 static int PosixSpawnImpl(void *ctx, RealSpawnPtr *real_posix_spawn, pid_t *pid,
                           const char *file_or_path, const void *file_actions,
                           const void *attrp, char *const argv[],
                           char *const envp[]) {
#endif
   INIT_SETPWENT;
   INIT_CLOCK_GETTIME;
   INIT_CLOCK_GETCPUCLOCKID;
   INIT_GETITIMER;
   INIT_TIME;
   INIT_GLOB;
   INIT_GLOB64;
   INIT___B64_TO;
+  INIT___DN_EXPAND;
   INIT_POSIX_SPAWN;
   INIT_WAIT;
   INIT_WAIT4;
   INIT_INET;
   INIT_PTHREAD_GETSCHEDPARAM;
   INIT_GETADDRINFO;
   INIT_GETNAMEINFO;
   INIT_GETSOCKNAME;

compiler-rt/lib/sanitizer_common/sanitizer_platform_interceptors.h

#define SANITIZER_INTERCEPT_CLOCK_GETTIME \
   (SI_FREEBSD || SI_NETBSD || SI_LINUX || SI_SOLARIS)
 #define SANITIZER_INTERCEPT_CLOCK_GETCPUCLOCKID \
   (SI_LINUX || SI_FREEBSD || SI_NETBSD)
 #define SANITIZER_INTERCEPT_GETITIMER SI_POSIX
 #define SANITIZER_INTERCEPT_TIME SI_POSIX
 #define SANITIZER_INTERCEPT_GLOB (SI_GLIBC || SI_SOLARIS)
 #define SANITIZER_INTERCEPT_GLOB64 SI_GLIBC
 #define SANITIZER_INTERCEPT___B64_TO SI_LINUX_NOT_ANDROID
+#define SANITIZER_INTERCEPT___DN_EXPAND SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_POSIX_SPAWN SI_POSIX
 #define SANITIZER_INTERCEPT_WAIT SI_POSIX
 #define SANITIZER_INTERCEPT_INET SI_POSIX
 #define SANITIZER_INTERCEPT_PTHREAD_GETSCHEDPARAM SI_POSIX
 #define SANITIZER_INTERCEPT_GETADDRINFO SI_POSIX
 #define SANITIZER_INTERCEPT_GETNAMEINFO SI_POSIX
 #define SANITIZER_INTERCEPT_GETSOCKNAME SI_POSIX
 #define SANITIZER_INTERCEPT_GETHOSTBYNAME SI_POSIX

compiler-rt/test/msan/Linux/dn_expand.cpp

+// RUN: %clangxx_msan -O0 %s -o %t -lresolv && %run %t
+// RUN: not %run %t READ 2>&1 | FileCheck %s --check-prefix=READ
+
+#include <assert.h>
+#include <resolv.h>
+#include <string.h>
+
+#include <sanitizer/msan_interface.h>
+
+void testRead() {
+  const int INPUT_LEN = 24;
+  char unsigned input[INPUT_LEN];
+  char output[1024];
+
+  dn_expand(input, input + sizeof(input), input + 23, output, sizeof(output));
+  // READ: Uninitialized bytes in __interceptor___dn_expand
+}
+
+void testWrite() {
+  char unsigned input[] = {0xff, 0xc5, 0xf7, 0xff, 0x00, 0x00, 0xff, 0x0a, 0x00,
+                           0x00, 0x00, 0x01, 0x00, 0x00, 0x02, 0x00, 0x01, 0x00,
+                           0x10, 0x01, 0x05, 0x00, 0x01, 0x0a, 0x67, 0x6f, 0x6f,
+                           0x67, 0x6c, 0x65, 0x2e, 0x63, 0x6f, 0x6d, 0x00};
+  char output[1024];
+
+  int res = dn_expand(input, input + sizeof(input), input + 23, output,
+                      sizeof(output));
+
+  assert(res >= 0);
+  __msan_check_mem_is_initialized(output, res);
+}
+
+void testWriteZeroLength() {
+  char unsigned input[] = {
+      0xff, 0xc5, 0xf7, 0xff, 0x00, 0x00, 0xff, 0x0a, 0x00, 0x00, 0x00, 0x01,
+      0x00, 0x00, 0x02, 0x00, 0x01, 0x00, 0x10, 0x01, 0x05, 0x00, 0x01, 0x00,
+  };
+  char output[1024];
+
+  int res = dn_expand(input, input + sizeof(input), input + 23, output,
+                      sizeof(output));
+
+  assert(res >= 0);
+  __msan_check_mem_is_initialized(output, res);
+}
+
+int main(int iArgc, const char *szArgv[]) {
+  const char *test = nullptr;
+  if (iArgc > 1) {
+    test = szArgv[1];
+  }
+
+  if (test == nullptr) {
+    testWrite();
+    testWriteZeroLength();
+  } else if (strcmp(test, "READ") == 0) {
+    testRead();
+  }
+
+  return 0;
+}

compiler-rt/test/sanitizer_common/TestCases/Linux/dn_expand.cpp

+// RUN: %clangxx %s -o %t -lresolv && %run %t %p
+
+#include <assert.h>
+#include <resolv.h>
+#include <string.h>
+
+#include <sanitizer/msan_interface.h>
+
+void testWrite() {
+  char unsigned input[] = {0xff, 0xc5, 0xf7, 0xff, 0x00, 0x00, 0xff, 0x0a, 0x00,
+                           0x00, 0x00, 0x01, 0x00, 0x00, 0x02, 0x00, 0x01, 0x00,
+                           0x10, 0x01, 0x05, 0x00, 0x01, 0x0a, 0x67, 0x6f, 0x6f,
+                           0x67, 0x6c, 0x65, 0x2e, 0x63, 0x6f, 0x6d, 0x00};
+  char output[1024];
+
+  int res = dn_expand(input, input + sizeof(input), input + 23, output,
+                      sizeof(output));
+
+  assert(res == 12);
+  assert(strcmp(output, "google\\.com") == 0);
+}
+
+void testWriteZeroLength() {
+  char unsigned input[] = {
+      0xff, 0xc5, 0xf7, 0xff, 0x00, 0x00, 0xff, 0x0a, 0x00, 0x00, 0x00, 0x01,
+      0x00, 0x00, 0x02, 0x00, 0x01, 0x00, 0x10, 0x01, 0x05, 0x00, 0x01, 0x00,
+  };
+  char output[1024];
+
+  int res = dn_expand(input, input + sizeof(input), input + 23, output,
+                      sizeof(output));
+
+  assert(res == 1);
+  assert(strcmp(output, "") == 0);
+}
+
+int main(int iArgc, const char *szArgv[]) {
+  testWrite();
+  testWriteZeroLength();
+
+  return 0;
+}