Uploaded image for project: 'JDK'
  1. JDK
  2. JDK-8236489

Java heap file on daxfs should be more secure

    XMLWordPrintable

Details

    • Enhancement
    • Resolution: Fixed
    • P4
    • 15
    • 14
    • hotspot
    • 10
    • b05

    Description

      https://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2019-December/037584.html

      HotSpot allocates Java heap on daxfs if we pass -XX:AllocateHeapAt.
      It performs open(2) and unlink(2) on daxfs, and it is used via mmap'ed address.

      mmap(2) would be called with MAP_SHARED, and it is not atomically between open(2) and unlink(2). If malicious user open Java heap file before unlink(2), it might be exposed.

      So I think we can use open(2) with O_TMPFILE instead of mkstemp(3).

      O_TMPFILE would create inode on filesystem, and it cannot be accessed from out-of-process.
      However it cannot be provided in older Linux kernel. So I keep current code as fall back.

         http://man7.org/linux/man-pages/man2/open.2.html

      Attachments

        Activity

          People

            ysuenaga Yasumasa Suenaga
            ysuenaga Yasumasa Suenaga
            Votes:
            0 Vote for this issue
            Watchers:
            3 Start watching this issue

            Dates

              Created:
              Updated:
              Resolved: