Prevent memory access violations when attempting to parse an x86_64 PE binary containing corrupt unwind information.

	PR 22113
incldue	* coff/pe.h (struct pex64_unwind_info): Add a rawUnwindCodesEnd
	field.

bfd	* pei-x86_64.c (pex64_get_unwind_info): Change to a boolean
	function.  Add an end address parameter.  Check access of the data
	pointer to make sure that they do not extend beyond the end
	address.  Return FALSE if any check fails.  Add the end address
	pointer to the ui structure.
	(pex64_xdata_print_uwd_codes): Check accesses of the raw unwind
	codes to make sure that they do not extend beyond the end address
	pointer.  Print an error message and return immediately if any
	check fails.

2 files changed, 59 insertions, 8 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 672143b..ddf0d04 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,16 @@
+2018-03-13  Nick Clifton  <nickc@redhat.com>
+
+	PR 22113
+	* pei-x86_64.c (pex64_get_unwind_info): Change to a boolean
+	function.  Add an end address parameter.  Check access of the data
+	pointer to make sure that they do not extend beyond the end
+	address.  Return FALSE if any check fails.  Add the end address
+	pointer to the ui structure.
+	(pex64_xdata_print_uwd_codes): Check accesses of the raw unwind
+	codes to make sure that they do not extend beyond the end address
+	pointer.  Print an error message and return immediately if any
+	check fails.
+
 2018-03-09  Nick Clifton  <nickc@redhat.com>
 
 	* elf64-s390.c (elf_s390_relocate_section): Move check for
diff --git a/bfd/pei-x86_64.c b/bfd/pei-x86_64.c
index db30726..3a0248d 100644
--- a/bfd/pei-x86_64.c
+++ b/bfd/pei-x86_64.c
@@ -98,14 +98,20 @@ pex64_get_runtime_function (bfd *abfd, struct pex64_runtime_function *rf,
 
 /* Swap in unwind info header.  */
 
-static void
-pex64_get_unwind_info (bfd *abfd, struct pex64_unwind_info *ui, void *data)
+static bfd_boolean
+pex64_get_unwind_info (bfd *abfd, struct pex64_unwind_info *ui,
+		       void *data, void *data_end)
 {
   struct external_pex64_unwind_info *ex_ui =
     (struct external_pex64_unwind_info *) data;
   bfd_byte *ex_dta = (bfd_byte *) data;
+  bfd_byte *ex_dta_end = (bfd_byte *) data_end;
 
   memset (ui, 0, sizeof (struct pex64_unwind_info));
+
+  if (ex_dta >= ex_dta_end || ex_dta + 4 >= ex_dta_end)
+    return FALSE;
+
   ui->Version = PEX64_UWI_VERSION (ex_ui->Version_Flags);
   ui->Flags = PEX64_UWI_FLAGS (ex_ui->Version_Flags);
   ui->SizeOfPrologue = (bfd_vma) ex_ui->SizeOfPrologue;
@@ -114,25 +120,33 @@ pex64_get_unwind_info (bfd *abfd, struct pex64_unwind_info *ui, void *data)
   ui->FrameOffset = PEX64_UWI_FRAMEOFF (ex_ui->FrameRegisterOffset);
   ui->sizeofUnwindCodes = PEX64_UWI_SIZEOF_UWCODE_ARRAY (ui->CountOfCodes);
   ui->SizeOfBlock = ui->sizeofUnwindCodes + 4;
-  ui->rawUnwindCodes = &ex_dta[4];
+  ui->rawUnwindCodes = ex_dta + 4;
+  ui->rawUnwindCodesEnd = ex_dta_end;
 
   ex_dta += ui->SizeOfBlock;
+  if (ex_dta >= ex_dta_end)
+    return FALSE;
+  
   switch (ui->Flags)
     {
     case UNW_FLAG_CHAININFO:
+      if (ex_dta + 12 >= ex_dta_end)
+	return FALSE;
       ui->rva_BeginAddress = bfd_get_32 (abfd, ex_dta + 0);
       ui->rva_EndAddress = bfd_get_32 (abfd, ex_dta + 4);
       ui->rva_UnwindData = bfd_get_32 (abfd, ex_dta + 8);
       ui->SizeOfBlock += 12;
-      return;
+      return TRUE;
     case UNW_FLAG_EHANDLER:
     case UNW_FLAG_UHANDLER:
     case UNW_FLAG_FHANDLER:
+      if (ex_dta + 4 >= ex_dta_end)
+	return FALSE;
       ui->rva_ExceptionHandler = bfd_get_32 (abfd, ex_dta);
       ui->SizeOfBlock += 4;
-      return;
+      return TRUE;
     default:
-      return;
+      return TRUE;
     }
 }
 
@@ -158,6 +172,12 @@ pex64_xdata_print_uwd_codes (FILE *file, bfd *abfd,
 
   i = 0;
 
+  if (ui->rawUnwindCodes + 1 >= ui->rawUnwindCodesEnd)
+    {
+      fprintf (file, _("warning: corrupt unwind data\n"));
+      return;
+    }
+
   if (ui->Version == 2
       && PEX64_UNWCODE_CODE (ui->rawUnwindCodes[1]) == UWOP_EPILOG)
     {
@@ -166,10 +186,18 @@ pex64_xdata_print_uwd_codes (FILE *file, bfd *abfd,
 	 to decode instruction flow if outside an epilog.  */
       unsigned int func_size = rf->rva_EndAddress - rf->rva_BeginAddress;
 
+      if (ui->rawUnwindCodes + 1 + (ui->CountOfCodes * 2) >= ui->rawUnwindCodesEnd)
+	{
+	  fprintf (file, _("warning: corrupt unwind data\n"));
+	  return;
+	}
+	  
       fprintf (file, "\tv2 epilog (length: %02x) at pc+:",
 	       ui->rawUnwindCodes[0]);
+
       if (PEX64_UNWCODE_INFO (ui->rawUnwindCodes[1]))
 	fprintf (file, " 0x%x", func_size - ui->rawUnwindCodes[0]);
+
       i++;
       for (; i < ui->CountOfCodes; i++)
 	{
@@ -187,6 +215,12 @@ pex64_xdata_print_uwd_codes (FILE *file, bfd *abfd,
       fputc ('\n', file);
     }
 
+  if (ui->rawUnwindCodes + 2 + (ui->CountOfCodes * 2) >= ui->rawUnwindCodesEnd)
+    {
+      fprintf (file, _("warning: corrupt unwind data\n"));
+      return;
+    }
+	  
   for (; i < ui->CountOfCodes; i++)
     {
       const bfd_byte *dta = ui->rawUnwindCodes + 2 * i;
@@ -338,14 +372,18 @@ pex64_dump_xdata (FILE *file, bfd *abfd,
       /* PR 17512: file: 2245-7442-0.004.  */
       if (end_addr > sec_size)
 	{
-	  fprintf (file, _("warning: xdata section corrupt"));
+	  fprintf (file, _("warning: xdata section corrupt\n"));
 	  end_addr = sec_size;
 	}
     }
   else
     end_addr = sec_size;
 
-  pex64_get_unwind_info (abfd, &ui, &xdata[addr]);
+  if (! pex64_get_unwind_info (abfd, &ui, xdata + addr, xdata + end_addr))
+    {
+      fprintf (file, _("warning: xdata section corrupt\n"));
+      return;
+    }
 
   if (ui.Version != 1 && ui.Version != 2)
     {