Fix crash when disassembling invalid range on powerpc vle

I got a report of a gdb crash for vle and further investigation showed an
attempt to disassemble an invalid memory range.  I tracked the crash down
to the code in get_powerpc_dialect, where we fail to make sure we have a
valid section pointer before dereferencing it.

There is no such problem for rs6000-based disassembling.

opcodes/ChangeLog:

2016-12-08  Luis Machado  <lgustavo@codesourcery.com>

	* ppc-dis.c (get_powerpc_dialect): Check NULL info->section.

2 files changed, 5 insertions, 1 deletions

diff --git a/opcodes/ChangeLog b/opcodes/ChangeLog
index ff9c689..09f0341 100644
--- a/opcodes/ChangeLog
+++ b/opcodes/ChangeLog
@@ -1,3 +1,7 @@
+2016-12-08  Luis Machado  <lgustavo@codesourcery.com>
+
+	* ppc-dis.c (get_powerpc_dialect): Check NULL info->section.
+
 2016-12-07  Maciej W. Rozycki  <macro@imgtec.com>
 
 	* mips-dis.c (print_mips16_insn_arg): Fix comment typo.
diff --git a/opcodes/ppc-dis.c b/opcodes/ppc-dis.c
index da1301e..efca157 100644
--- a/opcodes/ppc-dis.c
+++ b/opcodes/ppc-dis.c
@@ -236,7 +236,7 @@ get_powerpc_dialect (struct disassemble_info *info)
 
   /* Disassemble according to the section headers flags for VLE-mode.  */
   if (dialect & PPC_OPCODE_VLE
-      && info->section->owner != NULL
+      && info->section != NULL && info->section->owner != NULL
       && bfd_get_flavour (info->section->owner) == bfd_target_elf_flavour
       && elf_object_id (info->section->owner) == PPC32_ELF_DATA
       && (elf_section_flags (info->section) & SHF_PPC_VLE) != 0)