Re: [PATCH] Fix uninitialized elf_segment_map fields in rewrite_elf_program_header

[Joe Seymour <jseymour at codesourcery dot com>]

On 11/13/12 20:14, Joe Seymour wrote:
> When using objcopy to adjust section LMA's, via --change-section-lma, I'm
> observing errors of the form "<section name> can't be allocated in segment <number>"
> 
> This happens because elf_segment_map structure allocated in
> rewrite_elf_program_header isn't fully initialized (valgrind provides copious
> amounts of output as evidence of this). In this case p_vaddr_offset having a
> garbage value is the problem, however there are some other fields not obviously
> initialized:
> 
> p_align
> p_size
> header_size
> p_align_valid
> p_size_valid
> count
> sections
> 
> Elsewhere in rewrite_elf_program_header bfd_zalloc is used, instead of
> bfd_alloc. Therefore this patch seems appropriate. The structure definition
> elf/internal.h supports this assessment:
> 
> - The values of p_align and p_size are irrelevant as p_align_valid and
> p_size_valid will both be zero.
> 
> - The surrounding code sets both includes_filehdr and includes_phdrs to zero, so
> header_size should be irrelevant.
> 
> - No sections have been added to the segment yet so having zero count is
> appropriate, and sections is irrelevant. By the same logic it is appropriate
> that p_vaddr_offset be zero, as it records the difference between the segment
> vma and that for its first section.
> 
> Unfortunately the port I'm seeing this on isn't upstream, and I haven't managed
> to observe it for other targets. Hopefully this is trivial/obvious enough to be OK?
> 
> As I don't have commit access perhaps someone could commit for me, if this is
> accepted.
> 
> Thanks,
> 
> 2012-11-13  Joe Seymour  <jseymour@codesourcery.com>
> 
> 	* elf.c (rewrite_elf_program_header): Allocate elf_segment_map with
> 	bfd_zalloc, instead of bfd_alloc.

Sorry, that patch was against an old binutils. Here's one against HEAD:

2012-11-13  Joe Seymour  <jseymour@codesourcery.com>

	* elf.c (rewrite_elf_program_header): Allocate elf_segment_map with
	bfd_zalloc, instead of bfd_alloc.

diff --git a/bfd/elf.c b/bfd/elf.c
index f40e81b..b8bb6d3 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -6043,7 +6043,7 @@ rewrite_elf_program_header (bfd *ibfd, bfd *obfd)
 		 and carry on looping.  */
 	      amt = sizeof (struct elf_segment_map);
 	      amt += ((bfd_size_type) section_count - 1) * sizeof (asection *);
-	      map = (struct elf_segment_map *) bfd_alloc (obfd, amt);
+	      map = (struct elf_segment_map *) bfd_zalloc (obfd, amt);
 	      if (map == NULL)
 		{
 		  free (sections);