Merged corrupt input fixes to 2.16 branch

[Daniel Jacobowitz <drow at false dot org>]

I've merged these patches to 2.16.  2.16.1 is almost ready now; I'm hoping
to release it on Friday.

-- 
Daniel Jacobowitz
CodeSourcery, LLC

2005-05-29  Daniel Jacobowitz  <dan@codesourcery.com>

	Backport from mainline:
	2005-05-29  Jakub Jelinek  <jakub@redhat.com>
	* elfcode.h (elf_object_p): Fail if e_shoff != 0, e_shnum == 0 and
	first shdr has sh_size == 0.  Fail if e_shnum is large to cause
	arithmetic overflow when allocating the i_shdr array.
	Sanity check sh_link and sh_info fields.  Fix e_shstrndx sanity check.

	2005-05-18  H.J. Lu  <hongjiu.lu@intel.com>
	* elf.c (group_signature): Undo the last change. Check if the
	symbol table section is correct.

	2005-05-17  Nick Clifton  <nickc@redhat.com>
	* elf.c (group_signature): Check for a group section which is
	actually a (corrupt) symbol table section in disguise and prevent
	an infinite loop from occurring.

	2005-05-17  Tavis Ormandy <taviso@gentoo.org>
	* elf.c (bfd_section_from_shdr): Add sanity check when parsing
	dynamic sections.

	2005-05-09  Alan Modra  <amodra@bigpond.net.au>
	* elfcode.h (elf_object_p): Add more sanity checks on elf header.

Index: src/bfd/elf.c
===================================================================
RCS file: /cvs/src/src/bfd/elf.c,v
retrieving revision 1.270
diff -u -p -r1.270 elf.c
--- src/bfd/elf.c	6 Mar 2005 02:02:15 -0000	1.270
+++ src/bfd/elf.c	29 May 2005 22:04:09 -0000
@@ -443,8 +443,11 @@ group_signature (bfd *abfd, Elf_Internal
   Elf_External_Sym_Shndx eshndx;
   Elf_Internal_Sym isym;
 
-  /* First we need to ensure the symbol table is available.  */
-  if (! bfd_section_from_shdr (abfd, ghdr->sh_link))
+  /* First we need to ensure the symbol table is available.  Make sure
+     that it is a symbol table section.  */
+  hdr = elf_elfsections (abfd) [ghdr->sh_link];
+  if (hdr->sh_type != SHT_SYMTAB
+      || ! bfd_section_from_shdr (abfd, ghdr->sh_link))
     return NULL;
 
   /* Go read the symbol.  */
@@ -1733,6 +1736,9 @@ bfd_section_from_shdr (bfd *abfd, unsign
     case SHT_DYNAMIC:	/* Dynamic linking information.  */
       if (! _bfd_elf_make_section_from_shdr (abfd, hdr, name))
 	return FALSE;
+      if (hdr->sh_link > elf_numsections (abfd)
+	  || elf_elfsections (abfd)[hdr->sh_link] == NULL)
+	return FALSE;
       if (elf_elfsections (abfd)[hdr->sh_link]->sh_type != SHT_STRTAB)
 	{
 	  Elf_Internal_Shdr *dynsymhdr;
Index: src/bfd/elfcode.h
===================================================================
RCS file: /cvs/src/src/bfd/elfcode.h,v
retrieving revision 1.64
diff -u -p -r1.64 elfcode.h
--- src/bfd/elfcode.h	20 Feb 2005 14:59:07 -0000	1.64
+++ src/bfd/elfcode.h	29 May 2005 22:04:09 -0000
@@ -33,7 +33,7 @@ Foundation, Inc., 59 Temple Place - Suit
 /* Problems and other issues to resolve.
 
    (1)	BFD expects there to be some fixed number of "sections" in
-        the object file.  I.E. there is a "section_count" variable in the
+	the object file.  I.E. there is a "section_count" variable in the
 	bfd structure which contains the number of sections.  However, ELF
 	supports multiple "views" of a file.  In particular, with current
 	implementations, executable files typically have two tables, a
@@ -612,8 +612,13 @@ elf_object_p (bfd *abfd)
 
   if (i_ehdrp->e_shoff != 0)
     {
+      bfd_signed_vma where = i_ehdrp->e_shoff;
+
+      if (where != (file_ptr) where)
+	goto got_wrong_format_error;
+
       /* Seek to the section header table in the file.  */
-      if (bfd_seek (abfd, (file_ptr) i_ehdrp->e_shoff, SEEK_SET) != 0)
+      if (bfd_seek (abfd, (file_ptr) where, SEEK_SET) != 0)
 	goto got_no_match;
 
       /* Read the first section header at index 0, and convert to internal
@@ -625,11 +630,46 @@ elf_object_p (bfd *abfd)
       /* If the section count is zero, the actual count is in the first
 	 section header.  */
       if (i_ehdrp->e_shnum == SHN_UNDEF)
-	i_ehdrp->e_shnum = i_shdr.sh_size;
+	{
+	  i_ehdrp->e_shnum = i_shdr.sh_size;
+	  if (i_ehdrp->e_shnum != i_shdr.sh_size
+	      || i_ehdrp->e_shnum == 0)
+	    goto got_wrong_format_error;
+	}
 
       /* And similarly for the string table index.  */
       if (i_ehdrp->e_shstrndx == SHN_XINDEX)
-	i_ehdrp->e_shstrndx = i_shdr.sh_link;
+	{
+	  i_ehdrp->e_shstrndx = i_shdr.sh_link;
+	  if (i_ehdrp->e_shstrndx != i_shdr.sh_link)
+	    goto got_wrong_format_error;
+	}
+
+      /* Sanity check that we can read all of the section headers.
+	 It ought to be good enough to just read the last one.  */
+      if (i_ehdrp->e_shnum != 1)
+	{
+	  /* Check that we don't have a totally silly number of sections.  */
+	  if (i_ehdrp->e_shnum > (unsigned int) -1 / sizeof (x_shdr)
+	      || i_ehdrp->e_shnum > (unsigned int) -1 / sizeof (i_shdr))
+	    goto got_wrong_format_error;
+
+	  where += (i_ehdrp->e_shnum - 1) * sizeof (x_shdr);
+	  if (where != (file_ptr) where)
+	    goto got_wrong_format_error;
+	  if ((bfd_size_type) where <= i_ehdrp->e_shoff)
+	    goto got_wrong_format_error;
+
+	  if (bfd_seek (abfd, (file_ptr) where, SEEK_SET) != 0)
+	    goto got_no_match;
+	  if (bfd_bread (&x_shdr, sizeof x_shdr, abfd) != sizeof (x_shdr))
+	    goto got_no_match;
+
+	  /* Back to where we were.  */
+	  where = i_ehdrp->e_shoff + sizeof (x_shdr);
+	  if (bfd_seek (abfd, (file_ptr) where, SEEK_SET) != 0)
+	    goto got_no_match;
+	}
     }
 
   /* Allocate space for a copy of the section header table in
@@ -673,6 +713,20 @@ elf_object_p (bfd *abfd)
 	    goto got_no_match;
 	  elf_swap_shdr_in (abfd, &x_shdr, i_shdrp + shindex);
 
+	  /* Sanity check sh_link and sh_info.  */
+	  if (i_shdrp[shindex].sh_link >= num_sec
+	      || (i_shdrp[shindex].sh_link >= SHN_LORESERVE
+		  && i_shdrp[shindex].sh_link <= SHN_HIRESERVE))
+	    goto got_wrong_format_error;
+
+	  if (((i_shdrp[shindex].sh_flags & SHF_INFO_LINK)
+	       || i_shdrp[shindex].sh_type == SHT_RELA
+	       || i_shdrp[shindex].sh_type == SHT_REL)
+	      && (i_shdrp[shindex].sh_info >= num_sec
+		  || (i_shdrp[shindex].sh_info >= SHN_LORESERVE
+		      && i_shdrp[shindex].sh_info <= SHN_HIRESERVE)))
+	    goto got_wrong_format_error;
+
 	  /* If the section is loaded, but not page aligned, clear
 	     D_PAGED.  */
 	  if (i_shdrp[shindex].sh_size != 0
@@ -685,6 +739,17 @@ elf_object_p (bfd *abfd)
 	}
     }
 
+  /* A further sanity check.  */
+  if (i_ehdrp->e_shnum != 0)
+    {
+      if (i_ehdrp->e_shstrndx >= elf_numsections (abfd)
+	  || (i_ehdrp->e_shstrndx >= SHN_LORESERVE
+	      && i_ehdrp->e_shstrndx <= SHN_HIRESERVE))
+	goto got_wrong_format_error;
+    }
+  else if (i_ehdrp->e_shstrndx != 0)
+    goto got_wrong_format_error;
+
   /* Read in the program headers.  */
   if (i_ehdrp->e_phnum == 0)
     elf_tdata (abfd)->phdr = NULL;
@@ -1042,7 +1107,7 @@ elf_slurp_symbol_table (bfd *abfd, asymb
 	     symcount);
 
 	  /* Slurp in the symbols without the version information,
-             since that is more helpful than just quitting.  */
+	     since that is more helpful than just quitting.  */
 	  verhdr = NULL;
 	}
 
@@ -1107,7 +1172,7 @@ elf_slurp_symbol_table (bfd *abfd, asymb
 	    sym->symbol.section = bfd_abs_section_ptr;
 
 	  /* If this is a relocatable file, then the symbol value is
-             already section relative.  */
+	     already section relative.  */
 	  if ((abfd->flags & (EXEC_P | DYNAMIC)) != 0)
 	    sym->symbol.value -= sym->symbol.section->vma;