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.

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 960e48492c91107498e27c70454feef2141e23fe..c93141458040a43bbcdf9e1350dc3ae26b234a27 100644 (file)
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -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.

diff --git a/bfd/elf.c b/bfd/elf.c
index db1e076b554a83be5db6234c11e89d26805fb527..05031546f3f483b6920964f84e9558b0fda72a01 100644 (file)
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -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

diff --git a/ld/ChangeLog b/ld/ChangeLog
index cdcf9500c9e05cf9c9a142ff66cbee731ff92b94..236517ae5e862c64aab504ea1a30c59fe4020455 100644 (file)
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -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>

diff --git a/ld/testsuite/ld-x86-64/pr14207.d b/ld/testsuite/ld-x86-64/pr14207.d
index b71d705dd64003e8198472f9f09da3465fc4e0d8..6830d031c410f9af6c86d296ef204a56072c0c86 100644 (file)
--- 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
 
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