1 files changed, 54 insertions, 6 deletions

diff --git a/lib/msan/tests/msan_test.cc b/lib/msan/tests/msan_test.cc
index dd81c4d798f6..58f695e69e12 100644
--- a/lib/msan/tests/msan_test.cc
+++ b/lib/msan/tests/msan_test.cc
@@ -1581,7 +1581,8 @@ TEST(MemorySanitizer, strdup) {
 TEST(MemorySanitizer, strndup) {
   char buf[4] = "abc";
   __msan_poison(buf + 2, sizeof(*buf));
-  char *x = strndup(buf, 3);
+  char *x;
+  EXPECT_UMR(x = strndup(buf, 3));
   EXPECT_NOT_POISONED(x[0]);
   EXPECT_NOT_POISONED(x[1]);
   EXPECT_POISONED(x[2]);
@@ -1593,7 +1594,8 @@ TEST(MemorySanitizer, strndup_short) {
   char buf[4] = "abc";
   __msan_poison(buf + 1, sizeof(*buf));
   __msan_poison(buf + 2, sizeof(*buf));
-  char *x = strndup(buf, 2);
+  char *x;
+  EXPECT_UMR(x = strndup(buf, 2));
   EXPECT_NOT_POISONED(x[0]);
   EXPECT_POISONED(x[1]);
   EXPECT_NOT_POISONED(x[2]);
@@ -2203,10 +2205,51 @@ TEST(MemorySanitizer, localtime_r) {
   EXPECT_NE(0U, strlen(time.tm_zone));
 }
 
+#if !defined(__FreeBSD__)
+/* Creates a temporary file with contents similar to /etc/fstab to be used
+   with getmntent{_r}.  */
+class TempFstabFile {
+ public:
+   TempFstabFile() : fd (-1) { }
+   ~TempFstabFile() {
+     if (fd >= 0)
+       close (fd);
+   }
+
+   bool Create(void) {
+     snprintf(tmpfile, sizeof(tmpfile), "/tmp/msan.getmntent.tmp.XXXXXX");
+
+     fd = mkstemp(tmpfile);
+     if (fd == -1)
+       return false;
+
+     const char entry[] = "/dev/root / ext4 errors=remount-ro 0 1";
+     size_t entrylen = sizeof(entry);
+
+     size_t bytesWritten = write(fd, entry, entrylen);
+     if (entrylen != bytesWritten)
+       return false;
+
+     return true;
+   }
+
+   const char* FileName(void) {
+     return tmpfile;
+   }
+
+ private:
+  char tmpfile[128];
+  int fd;
+};
+#endif
+
 // There's no getmntent() on FreeBSD.
 #if !defined(__FreeBSD__)
 TEST(MemorySanitizer, getmntent) {
-  FILE *fp = setmntent("/etc/fstab", "r");
+  TempFstabFile fstabtmp;
+  ASSERT_TRUE(fstabtmp.Create());
+  FILE *fp = setmntent(fstabtmp.FileName(), "r");
+
   struct mntent *mnt = getmntent(fp);
   ASSERT_TRUE(mnt != NULL);
   ASSERT_NE(0U, strlen(mnt->mnt_fsname));
@@ -2222,7 +2265,10 @@ TEST(MemorySanitizer, getmntent) {
 // There's no getmntent_r() on FreeBSD.
 #if !defined(__FreeBSD__)
 TEST(MemorySanitizer, getmntent_r) {
-  FILE *fp = setmntent("/etc/fstab", "r");
+  TempFstabFile fstabtmp;
+  ASSERT_TRUE(fstabtmp.Create());
+  FILE *fp = setmntent(fstabtmp.FileName(), "r");
+
   struct mntent mntbuf;
   char buf[1000];
   struct mntent *mnt = getmntent_r(fp, &mntbuf, buf, sizeof(buf));
@@ -3678,8 +3724,10 @@ TEST(MemorySanitizer, ICmpRelational) {
 
   EXPECT_POISONED(poisoned(6, 0xF) > poisoned(7, 0));
   EXPECT_POISONED(poisoned(0xF, 0xF) > poisoned(7, 0));
-
-  EXPECT_NOT_POISONED(poisoned(-1, 0x80000000U) >= poisoned(-1, 0U));
+  // Note that "icmp op X, Y" is approximated with "or shadow(X), shadow(Y)"
+  // and therefore may generate false positives in some cases, e.g. the
+  // following one:
+  // EXPECT_NOT_POISONED(poisoned(-1, 0x80000000U) >= poisoned(-1, 0U));
 }
 
 #if MSAN_HAS_M128