elf: Properly compute offsets of note descriptor and next note

According to gABI, in a note entry, the note name field, not note name
size, is padded for the note descriptor.  And the note descriptor field,
not note descriptor size, is padded for the next note entry.  Also notes
are aligned to 4 bytes in 32-bit objects and 8 bytes in 64-bit objects.
Since on Linux, .note.ABI-tag and .note.gnu.build-id notes are always
aligned to 4 bytes, we need to use alignment of note section or note
segment, instead of assuming alignment based on ELF file class.

Tested on i686 and x86-64.

bfd/

	PR binutils/22444
	* elf.c (elf_read_notes): Add an argument for note aligment.
	(elf_parse_notes): Likewise.
	(_bfd_elf_make_section_from_shdr): Pass section aligment to
	elf_parse_notes.
	(bfd_section_from_phdr): Pass segment aligment to elf_read_notes.
	(elf_parse_notes): Add an argument for note aligment.  Use
	ELF_NOTE_DESC_OFFSET to get the offset of the note descriptor.
	Use ELF_NOTE_NEXT_OFFSET to get the offset of the next note
	entry.
	(elf_read_notes): Add an argument for note aligment and pass it
	to elf_parse_notes.

binutils/

	PR binutils/22444
	* readelf.c (process_notes_at): Use ELF_NOTE_DESC_OFFSET to get
	the offset of the note descriptor.  Use ELF_NOTE_NEXT_OFFSET to
	get the offset of the next note entry.

include/

	PR binutils/22444
	* elf/external.h (ELF_ALIGN_UP): New.
	(ELF_NOTE_DESC_OFFSET): Likewise.
	(ELF_NOTE_NEXT_OFFSET): Likewise.

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 55fe3b4e61e23419485cd4c2a90c3a4dc14fc347..0395dcf6ccabfddac5aef757348925f57efec742 100644 (file)
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,18 @@
+2017-11-24  H.J. Lu  <hongjiu.lu@intel.com>
+
+       PR binutils/22444
+       * elf.c (elf_read_notes): Add an argument for note aligment.
+       (elf_parse_notes): Likewise.
+       (_bfd_elf_make_section_from_shdr): Pass section aligment to
+       elf_parse_notes.
+       (bfd_section_from_phdr): Pass segment aligment to elf_read_notes.
+       (elf_parse_notes): Add an argument for note aligment.  Use
+       ELF_NOTE_DESC_OFFSET to get the offset of the note descriptor.
+       Use ELF_NOTE_NEXT_OFFSET to get the offset of the next note
+       entry.
+       (elf_read_notes): Add an argument for note aligment and pass it
+       to elf_parse_notes.
+
 2017-11-23  Alan Modra  <amodra@gmail.com>
 
        * elf32-hppa.c (pc_dynrelocs): Define.

diff --git a/bfd/elf.c b/bfd/elf.c
index 8cd67ad59bb8853ab915a2ba775556c32fe9b950..d42c949407f1dccf18ea55dd744ed15740b47ac9 100644 (file)
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -52,9 +52,10 @@ static int elf_sort_sections (const void *, const void *);
 static bfd_boolean assign_file_positions_except_relocs (bfd *, struct bfd_link_info *);
 static bfd_boolean prep_headers (bfd *);
 static bfd_boolean swap_out_syms (bfd *, struct elf_strtab_hash **, int) ;
-static bfd_boolean elf_read_notes (bfd *, file_ptr, bfd_size_type) ;
+static bfd_boolean elf_read_notes (bfd *, file_ptr, bfd_size_type,
+                                  size_t align) ;
 static bfd_boolean elf_parse_notes (bfd *abfd, char *buf, size_t size,
-                                   file_ptr offset);
+                                   file_ptr offset, size_t align);
 
 /* Swap version information in and out.  The version information is
    currently size independent.  If that ever changes, this code will
@@ -1089,7 +1090,8 @@ _bfd_elf_make_section_from_shdr (bfd *abfd,
       if (!bfd_malloc_and_get_section (abfd, newsect, &contents))
        return FALSE;
 
-      elf_parse_notes (abfd, (char *) contents, hdr->sh_size, hdr->sh_offset);
+      elf_parse_notes (abfd, (char *) contents, hdr->sh_size,
+                      hdr->sh_offset, hdr->sh_addralign);
       free (contents);
     }
 
@@ -2990,7 +2992,8 @@ bfd_section_from_phdr (bfd *abfd, Elf_Internal_Phdr *hdr, int hdr_index)
     case PT_NOTE:
       if (! _bfd_elf_make_section_from_phdr (abfd, hdr, hdr_index, "note"))
        return FALSE;
-      if (! elf_read_notes (abfd, hdr->p_offset, hdr->p_filesz))
+      if (! elf_read_notes (abfd, hdr->p_offset, hdr->p_filesz,
+                           hdr->p_align))
        return FALSE;
       return TRUE;
 
@@ -10970,14 +10973,14 @@ elfcore_write_register_note (bfd *abfd,
 }
 
 static bfd_boolean
-elf_parse_notes (bfd *abfd, char *buf, size_t size, file_ptr offset)
+elf_parse_notes (bfd *abfd, char *buf, size_t size, file_ptr offset,
+                size_t align)
 {
   char *p;
 
   p = buf;
   while (p < buf + size)
     {
-      /* FIXME: bad alignment assumption.  */
       Elf_External_Note *xnp = (Elf_External_Note *) p;
       Elf_Internal_Note in;
 
@@ -10992,7 +10995,7 @@ elf_parse_notes (bfd *abfd, char *buf, size_t size, file_ptr offset)
        return FALSE;
 
       in.descsz = H_GET_32 (abfd, xnp->descsz);
-      in.descdata = in.namedata + BFD_ALIGN (in.namesz, 4);
+      in.descdata = p + ELF_NOTE_DESC_OFFSET (in.namesz, align);
       in.descpos = offset + (in.descdata - buf);
       if (in.descsz != 0
          && (in.descdata >= buf + size
@@ -11054,14 +11057,15 @@ elf_parse_notes (bfd *abfd, char *buf, size_t size, file_ptr offset)
          break;
        }
 
-      p = in.descdata + BFD_ALIGN (in.descsz, 4);
+      p += ELF_NOTE_NEXT_OFFSET (in.namesz, in.descsz, align);
     }
 
   return TRUE;
 }
 
 static bfd_boolean
-elf_read_notes (bfd *abfd, file_ptr offset, bfd_size_type size)
+elf_read_notes (bfd *abfd, file_ptr offset, bfd_size_type size,
+               size_t align)
 {
   char *buf;
 
@@ -11080,7 +11084,7 @@ elf_read_notes (bfd *abfd, file_ptr offset, bfd_size_type size)
   buf[size] = 0;
 
   if (bfd_bread (buf, size, abfd) != size
-      || !elf_parse_notes (abfd, buf, size, offset))
+      || !elf_parse_notes (abfd, buf, size, offset, align))
     {
       free (buf);
       return FALSE;

diff --git a/binutils/ChangeLog b/binutils/ChangeLog
index 32df4b98f7618da42af24c79417827dad265b08e..eab683047ed9230b51461509819dfef206cf9c60 100644 (file)
--- a/binutils/ChangeLog
+++ b/binutils/ChangeLog
@@ -1,3 +1,10 @@
+2017-11-24  H.J. Lu  <hongjiu.lu@intel.com>
+
+       PR binutils/22444
+       * readelf.c (process_notes_at): Use ELF_NOTE_DESC_OFFSET to get
+       the offset of the note descriptor.  Use ELF_NOTE_NEXT_OFFSET to
+       get the offset of the next note entry.
+
 2017-11-23  Pavel I. Kryukov  <kryukov@frtk.ru>
 
        PR 22485

diff --git a/binutils/readelf.c b/binutils/readelf.c
index 5944ebee960bd65c520538e48a84696ca98a0c69..739367d899bc1332242a3f6e48ff370ea2751b03 100644 (file)
--- a/binutils/readelf.c
+++ b/binutils/readelf.c
@@ -17969,9 +17969,13 @@ process_notes_at (Filedata *           filedata,
          inote.namesz   = BYTE_GET (external->namesz);
          inote.namedata = external->name;
          inote.descsz   = BYTE_GET (external->descsz);
-         inote.descdata = inote.namedata + align_power (inote.namesz, 2);
+         inote.descdata = ((char *) external
+                           + ELF_NOTE_DESC_OFFSET (inote.namesz,
+                                                   section->sh_addralign));
          inote.descpos  = offset + (inote.descdata - (char *) pnotes);
-         next = inote.descdata + align_power (inote.descsz, 2);
+         next = ((char *) external
+                 + ELF_NOTE_NEXT_OFFSET (inote.namesz, inote.descsz,
+                                         section->sh_addralign));
        }
       else
        {

diff --git a/include/ChangeLog b/include/ChangeLog
index 670456cecea92027368dd4b7bcbaecca23756f89..a7668678f8644f391d52432bf8787df05c7253fc 100644 (file)
--- a/include/ChangeLog
+++ b/include/ChangeLog
@@ -1,3 +1,10 @@
+2017-11-24  H.J. Lu  <hongjiu.lu@intel.com>
+
+       PR binutils/22444
+       * elf/external.h (ELF_ALIGN_UP): New.
+       (ELF_NOTE_DESC_OFFSET): Likewise.
+       (ELF_NOTE_NEXT_OFFSET): Likewise.
+
 2017-11-16  Tamar Christina  <tamar.christina@arm.com>
 
        * opcode/aarch64.h: (AARCH64_FEATURE_F16_FML): New.

diff --git a/include/elf/external.h b/include/elf/external.h
index d65bae0b2187c6580a2deabd6c724d6da809888a..eb0a53a9a9c3bb1c3e9137df3bec5d2552286621 100644 (file)
--- a/include/elf/external.h
+++ b/include/elf/external.h
@@ -183,6 +183,22 @@ typedef struct {
   char         name[1];                /* Start of the name+desc data */
 } Elf_External_Note;
 
+/* Align an address upward to a boundary, expressed as a number of bytes.
+   E.g. align to an 8-byte boundary with argument of 8.  */
+#define ELF_ALIGN_UP(addr, boundary) \
+  (((bfd_vma) (addr) + ((boundary) - 1)) & ~ (bfd_vma) ((boundary) -1))
+
+/* Compute the offset of the note descriptor from size of note entry's
+   owner string and note alignment.  */
+#define ELF_NOTE_DESC_OFFSET(namesz, align) \
+  ELF_ALIGN_UP (offsetof (Elf_External_Note, name) + (namesz), (align))
+
+/* Compute the offset of the next note entry from size of note entry's
+   owner string, size of the note descriptor and note alignment.  */
+#define ELF_NOTE_NEXT_OFFSET(namesz, descsz, align) \
+  ELF_ALIGN_UP (ELF_NOTE_DESC_OFFSET ((namesz), (align)) + (descsz), \
+               (align))
+
 /* Relocation Entries */
 typedef struct {
   unsigned char r_offset[4];   /* Location at which to apply the action */