@TechReport{Dartmouth:TR2009-657,
  author = {Ashwin Ramaswamy and Sergey Bratus and Michael E. Locasto and Sean W. Smith},
  title = {{Katana: A Hot Patching Framework for ELF Executables}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2009-657},
  year = {2009},
  month = {September},
  URL = {http://www.cs.dartmouth.edu/reports/TR2009-657.pdf},
  abstract = {
      Despite advances in software modularity, security, and reliability,
    offline patching remains the predominant form of updating or
    protecting commodity software.  Unfortunately, the mechanics of hot
    patching (the process of upgrading a program while it executes) remain
    understudied, even though such a capability offers practical benefits
    for both consumer and mission-critical systems.
      A reliable hot patching procedure would serve particularly well by
    reducing the downtime necessary for critical functionality or security
    upgrades.  Yet, hot patching also carries the risk -- real or
    perceived -- of leaving the system in an inconsistent state, which
    leads many owners to forego its benefits as too risky.
      In this paper, we propose a novel method for hot patching ELF binaries
    that supports (a) synchronized global data and code updates and
    (b) reasoning about the results of applying the hot patch.  We propose
    a format, which we call a Patch Object, for encoding patches as a
    special type of ELF relocatable object file.  Our tool, Katana,
    automatically creates these patch objects as a by-product of the
    standard source build process.  Katana also allows an end-user to
    apply the Patch Objects to a running process.  In essence, our method
    can be viewed as an extension of the Application Binary Interface
    (ABI), and we argue for its inclusion in future ABI standards.  
  }
}