diff --git a/libs/binder/Parcel.cpp b/libs/binder/Parcel.cpp
index ba5688c..f61eaca 100644
--- a/libs/binder/Parcel.cpp
+++ b/libs/binder/Parcel.cpp
@@ -26,6 +26,7 @@
 #include <binder/TextOutput.h>
 
 #include <errno.h>
+#include <utils/CallStack.h>
 #include <utils/Debug.h>
 #include <utils/Log.h>
 #include <utils/String8.h>
@@ -767,6 +768,29 @@
 status_t Parcel::writeDupFileDescriptor(int fd)
 {
     int dupFd = dup(fd);
+
+    {   // Temporary extra debug validation for b/17477219: a Parcel recipient is
+        // getting a positive but invalid fd unexpectedly. Trying to track down
+        // where it's coming from.
+        int dupErrno = dupFd < 0 ? errno : 0;
+        int fdFlags = fcntl(fd, F_GETFD);
+        int fdFlagsErrno = fdFlags == -1 ? errno : 0;
+        int dupFlags = fcntl(dupFd, F_GETFD);
+        int dupFlagsErrno = dupFlags == -1 ? errno : 0;
+        if (dupFd < 0 || fdFlags == -1 || dupFlags == -1) {
+            ALOGE("Parcel::writeDupFileDescriptor failed:\n"
+                    "  fd=%d flags=%d err=%d(%s)\n"
+                    "  dupFd=%d dupErr=%d(%s) flags=%d err=%d(%s)",
+                    fd, fdFlags, fdFlagsErrno, strerror(fdFlagsErrno),
+                    dupFd, dupErrno, strerror(dupErrno),
+                    dupFlags, dupFlagsErrno, strerror(dupFlagsErrno));
+            if (fd < 0 || fdFlags == -1) {
+                CallStack(LOG_TAG);
+            }
+            return -errno;
+        }
+    }
+
     if (dupFd < 0) {
         return -errno;
     }
@@ -1297,6 +1321,7 @@
                 oldfd, fds[i], dupErrno, strerror(dupErrno),
                 oldfd, flags, fcntlErrno, strerror(fcntlErrno),
                 flat, flat ? flat->type : 0);
+            CallStack(LOG_TAG);
         }
     }