[PATCH RFC v7 00/22] XSA55 libelf fixes for Xen 4.1

[Ian Jackson <ian.jackson@eu.citrix.com>]

This is a backport of my series to try to fix libelf and the domain
loader.  It corresponds to v7 of the xen-unstable and 4.2 series.

This is available via git:
  http://xenbits.xen.org/gitweb/?p=people/iwj/xen-unstable.git;a=summary
  git://xenbits.xen.org/people/iwj/xen-unstable.git
in the commits
  xsa55-4.1-base-rebasing..xsa55-4.1-rebasing

Here is a summary of the series:

 01/21 libelf: abolish libelf-relocate.c
 02/21 libxc: introduce xc_dom_seg_to_ptr_pages
 03/21 libxc: Fix range checking in xc_dom_pfn_to_ptr etc.
 04/21 libelf: abolish elf_sval and elf_access_signed
 05/21 libelf/xc_dom_load_elf_symtab: Do not use "syms" uninitialised
 06/21 libelf: introduce macros for memory access and pointer handling
 07/21 tools/xcutils/readnotes: adjust print_l1_mfn_valid_note
 08/21 libelf: check nul-terminated strings properly
 09/21 libelf: check all pointer accesses
 10/21 libelf: Check pointer references in elf_is_elfbinary
 11/21 libelf: Make all callers call elf_check_broken
 12/21 libelf: use C99 bool for booleans
 13/21 libelf: use only unsigned integers
 14/21 libxc: Introduce xc_bitops.h
 15/21 libelf: check loops for running away
 16/21 libelf: abolish obsolete macros
 17/21 libxc: Add range checking to xc_dom_binloader
 18/21 DRAFT libxc: check failure of xc_dom_*_to_ptr, xc_map_foreign_range
 19/21 DRAFT libxc: check return values from malloc
 20/21 libxc: range checks in xc_dom_p2m_host and _guest
 21/21 libxc: check blob size before proceeding in xc_dom_check_gzip

Patches 18 and 19 shouldn't be considered definitive because I haven't
yet rerun the greps for affected code, and 4.1 might have some
instances that 4.2 doesn't which would also need to be fixed.

However, it seemed to me to be a good idea to send this backport out
as soon as possible for the benefit of people who are working with
older versions of Xen.