Bug 4499

Created attachment 1833 [details]
testcase

Program Headers:
  Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
  PHDR           0x00052c 0x0804a52c 0x0804a52c 0x00100 0x00100 R   0x4
  INTERP         0x000114 0x08048114 0x08048114 0x00013 0x00013 R   0x1
      [Requesting program interpreter: /lib/ld-linux.so.2]
  LOAD           0x00052c 0x0804a52c 0x0804a52c 0x0014a 0x0014a R   0x1000
  LOAD           0x00042c 0x0804942c 0x0804942c 0x00100 0x00104 RW  0x1000
  DYNAMIC        0x000440 0x08049440 0x08049440 0x000c8 0x000c8 RW  0x4
  NOTE           0x000128 0x08048128 0x08048128 0x00020 0x00020 R   0x4
  GNU_STACK      0x000000 0x00000000 0x00000000 0x00000 0x00000 RW  0x4
  LOAD           0x000000 0x08048000 0x08048000 0x0042c 0x0042c R E 0x1000

The basic problem here is that bfd can't cope with load segments that don't have
  increasing file offset.

What's more the first load segment contains the program headers, which tricks
these lines in elf.c
	  adjust = vma_page_aligned_bias (m->sections[0]->vma, off, align);
	  off += adjust;
We ought to be using the phdr vma rather than m->sections[0]->vma in this case.

>The basic problem here is that bfd can't cope with load segments that don't have
> increasing file offset.

I had to trick the linux kernel which also has problems to handle PT_PHDR
segments not in the first load, but even with the PT_LOAD segments in the good
order (that is sorted by p_vaddr as the norm requires), strip destroys the
executable.

The master branch has been updated by Alan Modra <amodra@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=30fe183248b2523ecff9da36853e2f893c4c4b91

commit 30fe183248b2523ecff9da36853e2f893c4c4b91
Author: Alan Modra <amodra@gmail.com>
Date:   Wed Oct 23 17:40:51 2019 +1030

    PR4499, assign file positions assumes segment offsets increasing
    
    This rewrites much of assign_file_positions_for_non_load_sections to
    allow objcopy and strip to handle cases like that in PR4499 where
    program headers were not in their usual position immediately after the
    ELF file header, and PT_LOAD headers were not sorted by paddr.
    
    	PR 4499
    include/
    	* elf/internal.h (struct elf_segment_map): Delete header_size.
    	Add no_sort_lma and idx.
    bfd/
    	* elf-nacl.c (nacl_modify_segment_map): Set no_sort_lma for all
    	PT_LOAD segments.
    	* elf32-spu.c (spu_elf_modify_segment_map): Likewise on overlay
    	PT_LOAD segments.
    	* elf.c (elf_sort_segments): New function.
    	(assign_file_positions_except_relocs): Use shortcuts to elfheader
    	and elf_tdata.  Seek to e_phoff not sizeof_ehdr to write program
    	headers.  Move PT_PHDR check..
    	(assign_file_positions_for_non_load_sections): ..and code setting
    	PT_PHDR p_vaddr and p_paddr, and code setting __ehdr_start value..
    	(assign_file_positions_for_load_sections): ..to here.  Sort
    	PT_LOAD headers.  Delete header_pad code.  Use actual number of
    	headers rather than allocated in calculating size for program
    	headers.  Don't assume program headers follow ELF file header.
    	Simplify pt_load_count code.  Only set "off" for PT_LOAD or
    	PT_NOTE in cores.
    	(rewrite_elf_program_header): Set p_vaddr_offset for segments
    	that include file and program headers.
    	(copy_elf_program_header): Likewise, replacing header_size code.

Fixed.