[COMMITTED] libdw: Don't pass NULL to dwarf_peel_type

[Mark Wielaard <mark@klomp.org>]

commit c3a6a9dfc "libdw: Use signedness of subrange type to
determine array bounds" introduced a type check on a DIE which
exposed a latent bug in the get_type function. Even if the type
of a DIE couldn't be determined it would call dwarf_peel_type
on it. The gcc undefined sanitizer would flag this as being
undefined behaviour because the second argument of the function
is marked as non-NULL. Fix this by checking we actually have
a non-NULL type DIE.

Signed-off-by: Mark Wielaard <mark@klomp.org>
---
 libdw/ChangeLog              | 5 +++++
 libdw/dwarf_aggregate_size.c | 2 +-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/libdw/ChangeLog b/libdw/ChangeLog
index 4275b830..311f34b5 100644
--- a/libdw/ChangeLog
+++ b/libdw/ChangeLog
@@ -1,3 +1,8 @@
+2021-10-18  Mark Wielaard  <mark@klomp.org>
+
+	* dwarf_aggregate_size.c (get_type): Don't pass NULL to
+	dwarf_peel_type.
+
 2021-10-06  Mark Wielaard  <mark@klomp.org>
 
 	* dwarf_aggregate_size.c (array_size): Check signedness of child DIE
diff --git a/libdw/dwarf_aggregate_size.c b/libdw/dwarf_aggregate_size.c
index 96023d69..89f2029e 100644
--- a/libdw/dwarf_aggregate_size.c
+++ b/libdw/dwarf_aggregate_size.c
@@ -40,7 +40,7 @@ get_type (Dwarf_Die *die, Dwarf_Attribute *attr_mem, Dwarf_Die *type_mem)
   Dwarf_Die *type = INTUSE(dwarf_formref_die)
     (INTUSE(dwarf_attr_integrate) (die, DW_AT_type, attr_mem), type_mem);
 
-  if (INTUSE(dwarf_peel_type) (type, type) != 0)
+  if (type == NULL || INTUSE(dwarf_peel_type) (type, type) != 0)
     return NULL;
 
   return type;
-- 
2.18.4