asan: null dereference in read_and_display_attr_value

This fixes multiple places in read_and_display_attr_value dealing with
range and location lists that can segfault when debug_info_p is NULL.
Fuzzed object files can contain arbitrary DW_FORMs.

	* dwarf.c (read_and_display_attr_value): Don't dereference NULL
	debug_info_p.

diff --git a/binutils/dwarf.c b/binutils/dwarf.c
index 2f4bb30ffd344fb816e2bcfc7c9b999d45ed0125..584c737b9ecc6f5d3da3fbfbe90b395457b1d607 100644 (file)
--- a/binutils/dwarf.c
+++ b/binutils/dwarf.c
@@ -2770,7 +2770,9 @@ read_and_display_attr_value (unsigned long attribute,
 
          if (form == DW_FORM_loclistx)
            {
-             if (dwo)
+             if (debug_info_p == NULL )
+               idx = (uint64_t) -1;
+             else if (dwo)
                {
                  idx = fetch_indexed_offset (uvalue, loclists_dwo,
                                              debug_info_p->loclists_base,
@@ -2778,7 +2780,7 @@ read_and_display_attr_value (unsigned long attribute,
                  if (idx != (uint64_t) -1)
                    idx += (offset_size == 8) ? 20 : 12;
                }
-             else if (debug_info_p == NULL || dwarf_version > 4)
+             else if (dwarf_version > 4)
                {
                  idx = fetch_indexed_offset (uvalue, loclists,
                                              debug_info_p->loclists_base,
@@ -2803,21 +2805,12 @@ read_and_display_attr_value (unsigned long attribute,
            }
          else if (form == DW_FORM_rnglistx)
            {
-             if (dwo)
-               {
-                 idx = fetch_indexed_offset (uvalue, rnglists,
-                                             debug_info_p->rnglists_base,
-                                             debug_info_p->offset_size);
-               }
+             if (debug_info_p == NULL)
+               idx = (uint64_t) -1;
              else
-               {
-                 if (debug_info_p == NULL)
-                   base = 0;
-                 else
-                   base = debug_info_p->rnglists_base;
-                 idx = fetch_indexed_offset (uvalue, rnglists, base,
-                                             debug_info_p->offset_size);
-               }
+               idx = fetch_indexed_offset (uvalue, rnglists,
+                                           debug_info_p->rnglists_base,
+                                           debug_info_p->offset_size);
            }
          else
            {