Uploaded image for project: 'JDK'
  1. JDK
  2. JDK-4063401

clinit_buffer may not be freed in FreeClasses()

    Details

    • Subcomponent:
    • Resolved In Build:
      1.2alpha2
    • CPU:
      generic
    • OS:
      solaris_2.5.1
    • Verification:
      Not verified

      Description


      I've poked around a bit and this does appear to be a bug. (OSF
      first brought this to my attention). Looks like we assume that the
      code attribute will always come before any exception attributes in
      the classfile ....

      The allocation mechanism has been optimized so that most of the datas are
      allocated in two buffers, malloc_buffer and clinit_buffer. Moreover,
      freeClass() assumes that this buffers can be freed by freeing
      cbConstantPool(cb) and <clinit>()V->code (when it exists).
      It seems that cbConstantPool(cb) is indeed the first allocation made in
      malloc_buffer but it may be false for <clinit>()V->code. According to the
      class format pecification, the "Exception" attribute could come before the
      "Code" attribute. In that case, <clinit>()V->code does no longer correspond
      to clinit_buffer. Thus, the clinit_buffer is not freed (memory loss) and
      free() is called with a bad address... We have fixed this problem by ensuring
      that they are indeed allocated at the begining of their respective buffers.
      Allocation start at the end of the buffers until the right allocation are
      made. After these allocations, the old allocation scheme is used. We could
      also fix this bug by keeping the values malloc_buffer and clinit_buffer int
      the method table structure (consuming just a bit more memory).

        Attachments

          Activity

            People

            • Assignee:
              pbk Peter Kessler
              Reporter:
              duke J. Duke (Inactive)
            • Votes:
              0 Vote for this issue
              Watchers:
              0 Start watching this issue

              Dates

              • Created:
                Updated:
                Resolved:
                Imported:
                Indexed: