[Bug binutils/22829] New: objcopy/strip: PT_GNU_RELRO is removed when it's not at the beginning of a PT_LOAD area

[ngg at tresorit dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=22829

            Bug ID: 22829
           Summary: objcopy/strip: PT_GNU_RELRO is removed when it's not
                    at the beginning of a PT_LOAD area
           Product: binutils
           Version: 2.31 (HEAD)
            Status: UNCONFIRMED
          Severity: critical
          Priority: P2
         Component: binutils
          Assignee: unassigned at sourceware dot org
          Reporter: ngg at tresorit dot com
  Target Milestone: ---

The assign_file_positions_for_non_load_sections() function in bfd/elf.c removes
a PT_GNU_RELRO segment if there is no corresponding PT_LOAD segment. This check
is made by comparing the two segments' p_paddr fields for equality.

The lld linker can assign a single PT_LOAD for multiple sections even if only
some of those will be marked as relro. In this case the p_paddr fields do not
match and strip/objcopy wrongfully removes the PT_GNU_RELRO segment.

Unfortunately it's not that easy to fix because if the equality check is fixed
to recognize an overlapping PT_LOAD segment then that segment's parameters
(vaddr, paddr, offset, ...) override the PT_GNU_RELRO segment's parameters
which is not what we would want.

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