Don't attempt to validate invalid DBus-passed file descriptors.

If an invalid file descriptor (i.e. -1) is passed over DBus then it is
impossible to determine if it is valid because the value() accessor
requires CheckValidity() to be called first and this will trigger a
DCHECK in base::File::GetInfo() because the file descriptor is invalid.
The solution is to abort the validity check if file.IsValid() is false.
This way after calling CheckValidity() is_valid() will indicate either
that the file descriptor was unsafe (i.e. a directory) or invalid (i.e.
-1).

BUG=496469

Review URL: https://codereview.chromium.org/1211093002

Cr-Commit-Position: refs/heads/master@{#336276}

1 files changed, 5 insertions, 0 deletions

diff --git a/dbus/file_descriptor.cc b/dbus/file_descriptor.cc
index c67a9e1..c740f28 100644
--- a/dbus/file_descriptor.cc
+++ b/dbus/file_descriptor.cc
@@ -49,6 +49,11 @@ int FileDescriptor::TakeValue() {
 
 void FileDescriptor::CheckValidity() {
   base::File file(value_);
+  if (!file.IsValid()) {
+    valid_ = false;
+    return;
+  }
+
   base::File::Info info;
   bool ok = file.GetInfo(&info);
   file.TakePlatformFile();  // Prevent |value_| from being closed by |file|.