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PR22829, objcopy/strip removes PT_GNU_RELRO from lld binaries

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lld lays out the relro segment differently to GNU ld, not bothering to
include the first few bytes of .got.plt and padding out to a page at
the end of the segment.  This patch teaches binutils to recognize the
different (and somewhat inferior) layout as valid.

bfd/
	PR 22829
	* elf.c (assign_file_positions_for_non_load_sections): Rewrite
	PT_GNU_RELRO setup.
ld/
	* testsuite/ld-x86-64/pr14207.d: Adjust relro p_filesz.
This commit is contained in:
Alan Modra 2018-02-12 13:06:07 +10:30
parent 387cd15b93
commit f2731e0c37
4 changed files with 62 additions and 28 deletions
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6
bfd/ChangeLog
View file

@ -1,3 +1,9 @@
2018-02-13 Alan Modra <amodra@gmail.com>
PR 22829
* elf.c (assign_file_positions_for_non_load_sections): Rewrite
PT_GNU_RELRO setup.
2018-02-12 Zebediah Figura <z.figura12@gmail.com>
* i386msdos.c (msdos_mkobject); New function.

78
bfd/elf.c
View file

@ -5861,50 +5861,74 @@ assign_file_positions_for_non_load_sections (bfd *abfd,
{
if (p->p_type == PT_GNU_RELRO)
{
const Elf_Internal_Phdr *lp;
struct elf_segment_map *lm;
bfd_vma start, end;
if (link_info != NULL)
{
/* During linking the range of the RELRO segment is passed
in link_info. */
in link_info. Note that there may be padding between
relro_start and the first RELRO section. */
start = link_info->relro_start;
end = link_info->relro_end;
}
else if (m->count != 0)
{
if (!m->p_size_valid)
abort ();
start = m->sections[0]->vma;
end = start + m->p_size;
}
else
{
start = 0;
end = 0;
}
if (start < end)
{
struct elf_segment_map *lm;
const Elf_Internal_Phdr *lp;
unsigned int i;
/* Find a LOAD segment containing a section in the RELRO
segment. */
for (lm = elf_seg_map (abfd), lp = phdrs;
lm != NULL;
lm = lm->next, lp++)
{
if (lp->p_type == PT_LOAD
&& lp->p_vaddr < link_info->relro_end
&& lm->count != 0
&& lm->sections[0]->vma >= link_info->relro_start)
&& lm->sections[lm->count - 1]->vma >= start
&& lm->sections[0]->vma < end)
break;
}
BFD_ASSERT (lm != NULL);
}
else
{
/* Otherwise we are copying an executable or shared
library, but we need to use the same linker logic. */
for (lp = phdrs; lp < phdrs + count; ++lp)
/* Find the section starting the RELRO segment. */
for (i = 0; i < lm->count; i++)
{
if (lp->p_type == PT_LOAD
&& lp->p_paddr == p->p_paddr)
asection *s = lm->sections[i];
if (s->vma >= start
&& s->vma < end
&& s->size != 0)
break;
}
}
BFD_ASSERT (i < lm->count);
p->p_vaddr = lm->sections[i]->vma;
p->p_paddr = lm->sections[i]->lma;
p->p_offset = lm->sections[i]->filepos;
p->p_memsz = end - p->p_vaddr;
p->p_filesz = p->p_memsz;
/* The RELRO segment typically ends a few bytes into
.got.plt but other layouts are possible. In cases
where the end does not match any loaded section (for
instance is in file padding), trim p_filesz back to
correspond to the end of loaded section contents. */
if (p->p_filesz > lp->p_vaddr + lp->p_filesz - p->p_vaddr)
p->p_filesz = lp->p_vaddr + lp->p_filesz - p->p_vaddr;
if (lp < phdrs + count)
{
p->p_vaddr = lp->p_vaddr;
p->p_paddr = lp->p_paddr;
p->p_offset = lp->p_offset;
if (link_info != NULL)
p->p_filesz = link_info->relro_end - lp->p_vaddr;
else if (m->p_size_valid)
p->p_filesz = m->p_size;
else
abort ();
p->p_memsz = p->p_filesz;
/* Preserve the alignment and flags if they are valid. The
gold linker generates RW/4 for the PT_GNU_RELRO section.
It is better for objcopy/strip to honor these attributes

4
ld/ChangeLog
View file

@ -1,3 +1,7 @@
2018-02-13 Alan Modra <amodra@gmail.com>
* testsuite/ld-x86-64/pr14207.d: Adjust relro p_filesz.
2018-02-07 Alan Modra <amodra@gmail.com>
Revert 2018-01-17 Alan Modra <amodra@gmail.com>

2
ld/testsuite/ld-x86-64/pr14207.d
View file

@ -13,7 +13,7 @@ Program Headers:
LOAD 0x000000 0x0000000000000000 0x0000000000000000 0x0001c8 0x0001c8 R 0x200000
LOAD 0x000b.8 0x0000000000200b.8 0x0000000000200b.8 0x0004.0 0x000c.8 RW 0x200000
DYNAMIC 0x000b.0 0x0000000000200b.0 0x0000000000200b.0 0x0001.0 0x0001.0 RW 0x8
GNU_RELRO 0x000b.8 0x0000000000200b.8 0x0000000000200b.8 0x0004.8 0x0004.8 R 0x1
GNU_RELRO 0x000b.8 0x0000000000200b.8 0x0000000000200b.8 0x0004.0 0x0004.8 R 0x1
Section to Segment mapping:
Segment Sections...