PR26348, Malloc error in write_zeros

This adds a few more sanity checks on ELF objects, and a BFD flag to
disable objcopy and strip when fuzzed input files belong in the "too
hard" basket.

bfd/
	PR 26348
	* bfd.c (struct bfd): Add read_only.
	* elfcode.h (elf_swap_shdr_in): Test both sh_offset and sh_size.
	Set read_only on warning.
	(elf_object_p): Sanity check program header alignment.  Set
	read_only on warning.
	* bfd-in2.h: Regenerate.
binutils/
	PR 26348
	* objcopy.c (copy_object): Report file name with endian error.
	Error and return on abfd->read_only.

4 files changed, 35 insertions, 5 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index a234258..0e22506 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,13 @@
+2020-08-13  Alan Modra  <amodra@gmail.com>
+
+	PR 26348
+	* bfd.c (struct bfd): Add read_only.
+	* elfcode.h (elf_swap_shdr_in): Test both sh_offset and sh_size.
+	Set read_only on warning.
+	(elf_object_p): Sanity check program header alignment.  Set
+	read_only on warning.
+	* bfd-in2.h: Regenerate.
+
 2020-08-12  Jon Turney  <jon.turney@dronecode.org.uk>
 
 	* elf.c (elfcore_grok_win32pstatus): Use unsigned int for
diff --git a/bfd/bfd-in2.h b/bfd/bfd-in2.h
index 35ef4d7..94d3195 100644
--- a/bfd/bfd-in2.h
+++ b/bfd/bfd-in2.h
@@ -6678,6 +6678,10 @@ struct bfd
   /* Set if this is a slim LTO object not loaded with a compiler plugin.  */
   unsigned int lto_slim_object : 1;
 
+  /* Do not attempt to modify this file.  Set when detecting errors
+     that BFD is not prepared to handle for objcopy/strip.  */
+  unsigned int read_only : 1;
+
   /* Set to dummy BFD created when claimed by a compiler plug-in
      library.  */
   bfd *plugin_dummy_bfd;
diff --git a/bfd/bfd.c b/bfd/bfd.c
index 538bdfa..ec38a06 100644
--- a/bfd/bfd.c
+++ b/bfd/bfd.c
@@ -245,6 +245,10 @@ CODE_FRAGMENT
 .  {* Set if this is a slim LTO object not loaded with a compiler plugin.  *}
 .  unsigned int lto_slim_object : 1;
 .
+.  {* Do not attempt to modify this file.  Set when detecting errors
+.     that BFD is not prepared to handle for objcopy/strip.  *}
+.  unsigned int read_only : 1;
+.
 .  {* Set to dummy BFD created when claimed by a compiler plug-in
 .     library.  *}
 .  bfd *plugin_dummy_bfd;
diff --git a/bfd/elfcode.h b/bfd/elfcode.h
index 2e2c534..84b08b5 100644
--- a/bfd/elfcode.h
+++ b/bfd/elfcode.h
@@ -321,11 +321,14 @@ elf_swap_shdr_in (bfd *abfd,
     {
       ufile_ptr filesize = bfd_get_file_size (abfd);
 
-      if (filesize != 0 && dst->sh_size > filesize)
-	_bfd_error_handler
-	  (_("warning: %pB has a corrupt section with a size (%"
-	     BFD_VMA_FMT "x) larger than the file size"),
-	   abfd, dst->sh_size);
+      if (filesize != 0
+	  && ((ufile_ptr) dst->sh_offset > filesize
+	      || dst->sh_size > filesize - dst->sh_offset))
+	{
+	  abfd->read_only = 1;
+	  _bfd_error_handler (_("warning: %pB has a section "
+				"extending past end of file"), abfd);
+	}
     }
   dst->sh_link = H_GET_32 (abfd, src->sh_link);
   dst->sh_info = H_GET_32 (abfd, src->sh_info);
@@ -764,6 +767,7 @@ elf_object_p (bfd *abfd)
 	     So we are kind, and reset the string index value to 0
 	     so that at least some processing can be done.  */
 	  i_ehdrp->e_shstrndx = SHN_UNDEF;
+	  abfd->read_only = 1;
 	  _bfd_error_handler
 	    (_("warning: %pB has a corrupt string table index - ignoring"),
 	     abfd);
@@ -804,6 +808,14 @@ elf_object_p (bfd *abfd)
 	  if (bfd_bread (&x_phdr, sizeof x_phdr, abfd) != sizeof x_phdr)
 	    goto got_no_match;
 	  elf_swap_phdr_in (abfd, &x_phdr, i_phdr);
+	  /* Too much code in BFD relies on alignment being a power of
+	     two, as required by the ELF spec.  */
+	  if (i_phdr->p_align != (i_phdr->p_align & -i_phdr->p_align))
+	    {
+	      abfd->read_only = 1;
+	      _bfd_error_handler (_("warning: %pB has a program header "
+				    "with invalid alignment"), abfd);
+	    }
 	}
     }