From 5598e24ef8aef14727ff72eea71ec460200bc2e3 Mon Sep 17 00:00:00 2001

From: Mark Wielaard <mark@klomp.org>

Date: Fri, 17 Mar 2017 21:03:35 +0100

Subject: [PATCH] debugedit: Fix cross-endian build-id reading and updating

 section data.

debugedit doesn't read raw mmap data any longer. Which made the complex

way to read the build-id unnecessary (and it was broken for cross-endian).

Just use gelf_getnote to read the notes.

Also in some special cases when only the debug_info or build_id data

was updated, but no section changed size and we had to preserve the

allocated section headers we could hit a bug in elfutils that could

trash some section data in case there were gaps between non-dirty and

dirty sections. See https://sourceware.org/bugzilla/show_bug.cgi?id=21199

Add a workaround for that issue.

This fixes the kompose package build on fedora ppc64.

And makes it possible to replicate that issue on x86_64.

Signed-off-by: Mark Wielaard <mark@klomp.org>

(cherry picked from commit a6e767600309bdb1f8af33b44563a1187fb0dbc4)

---

 tools/debugedit.c | 63 +++++++++++++++++++++++++++----------------------------

 1 file changed, 31 insertions(+), 32 deletions(-)

diff --git a/tools/debugedit.c b/tools/debugedit.c

index 87a423fdb..0f373162d 100644

--- a/tools/debugedit.c

+++ b/tools/debugedit.c

@@ -2581,40 +2581,25 @@ main (int argc, char *argv[])

 	  break;

 	case SHT_NOTE:

 	  if (do_build_id

-	      && build_id == NULL && (dso->shdr[i].sh_flags & SHF_ALLOC))

+	      && build_id == 0 && (dso->shdr[i].sh_flags & SHF_ALLOC))

 	    {

 	      /* Look for a build-ID note here.  */

+	      size_t off = 0;

+	      GElf_Nhdr nhdr;

+	      size_t name_off;

+	      size_t desc_off;

 	      Elf_Data *data = elf_getdata (elf_getscn (dso->elf, i), NULL);

-	      Elf32_Nhdr nh;

-	      Elf_Data dst =

-		{

-		  .d_version = EV_CURRENT, .d_type = ELF_T_NHDR,

-		  .d_buf = &nh, .d_size = sizeof nh

-		};

-	      Elf_Data src = dst;

-	      src.d_buf = data->d_buf;

-	      assert (sizeof (Elf32_Nhdr) == sizeof (Elf64_Nhdr));

-	      while ((char *) data->d_buf + data->d_size -

-		     (char *) src.d_buf > (int) sizeof nh

-		     && elf32_xlatetom (&dst, &src, dso->ehdr.e_ident[EI_DATA]))

-		{

-		  Elf32_Word len = sizeof nh + nh.n_namesz;

-		  len = (len + 3) & ~3;

-

-		  if (nh.n_namesz == sizeof "GNU" && nh.n_type == 3

-		      && !memcmp ((char *) src.d_buf + sizeof nh, "GNU", sizeof "GNU"))

-		    {

-		      build_id = data;

-		      build_id_offset = (char *) src.d_buf + len -

-					(char *) data->d_buf;

-		      build_id_size = nh.n_descsz;

-		      break;

-		    }

-

-		  len += nh.n_descsz;

-		  len = (len + 3) & ~3;

-		  src.d_buf = (char *) src.d_buf + len;

-		}

+	      while ((off = gelf_getnote (data, off,

+					  &nhdr, &name_off, &desc_off)) > 0)

+		if (nhdr.n_type == NT_GNU_BUILD_ID

+		    && nhdr.n_namesz == sizeof "GNU"

+		    && (memcmp ((char *)data->d_buf + name_off, "GNU",

+				sizeof "GNU") == 0))

+		  {

+		    build_id = data;

+		    build_id_offset = desc_off;

+		    build_id_size = nhdr.n_descsz;

+		  }

 	    }

 	  break;

 	default:

@@ -2622,6 +2607,20 @@ main (int argc, char *argv[])

 	}

     }

+  /* Normally we only need to explicitly update the section headers

+     and data when any section data changed size. But because of a bug

+     in elfutils before 0.169 we will have to update and write out all

+     section data if any data has changed (when ELF_F_LAYOUT was

+     set). https://sourceware.org/bugzilla/show_bug.cgi?id=21199 */

+  bool need_update = need_strp_update || need_stmt_update;

+

+#if !_ELFUTILS_PREREQ (0, 169)

+  /* string replacements or build_id updates don't change section size. */

+  need_update = (need_update

+		 || need_string_replacement

+		 || (do_build_id && build_id != NULL));

+#endif

+

   /* We might have changed the size of some debug sections. If so make

      sure the section headers are updated and the data offsets are

      correct. We set ELF_F_LAYOUT above because we don't want libelf

@@ -2631,7 +2630,7 @@ main (int argc, char *argv[])

      anything for the phdrs allocated sections. Keep the offset of

      allocated sections so they are at the same place in the file. Add

      unallocated ones after the allocated ones. */

-  if (dso->phnum != 0 && (need_strp_update || need_stmt_update))

+  if (dso->phnum != 0 && need_update)

     {

       Elf *elf = dso->elf;

       GElf_Off last_offset;