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From 3b56a1358768563d9cf320559ebdedfb30f122dd Mon Sep 17 00:00:00 2001
From: Alan Modra <amodra@gmail.com>
Date: Mon, 12 Feb 2018 13:06:07 +1030
Subject: [PATCH] PR22829, objcopy/strip removes PT_GNU_RELRO from lld binaries
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.
(cherry picked from commit f2731e0c374e5323ce4cdae2bcc7b7fe22da1a6f)
---
bfd/elf.c | 78 ++++++++++++++++++++++++++--------------
ld/testsuite/ld-x86-64/pr14207.d | 2 +-
2 files changed, 52 insertions(+), 28 deletions(-)
diff --git a/bfd/elf.c b/bfd/elf.c
index bbaab26918..f5a230cd77 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -5826,50 +5826,74 @@ 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
diff --git a/ld/testsuite/ld-x86-64/pr14207.d b/ld/testsuite/ld-x86-64/pr14207.d
index f6558e7cd7..41f92b8bd8 100644
--- a/ld/testsuite/ld-x86-64/pr14207.d
+++ b/ld/testsuite/ld-x86-64/pr14207.d
@@ -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...
--
2.16.2
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