We need to check the cuoff points to a real Dwarf_Die before trying to
intern the cu with tsearch. Otherwise bogus keys might end up in the
search tree with NULL cus. That will cause crashes in compare_cukey
during next insertion or deletion of cus.

https://bugzilla.redhat.com/show_bug.cgi?id=1170810#c30

Signed-off-by: Mark Wielaard <[email protected]>
---
 libdwfl/ChangeLog |  5 +++++
 libdwfl/cu.c      | 15 ++++++---------
 2 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/libdwfl/ChangeLog b/libdwfl/ChangeLog
index 6945eec..bce113e 100644
--- a/libdwfl/ChangeLog
+++ b/libdwfl/ChangeLog
@@ -1,5 +1,10 @@
 2015-05-05  Mark Wielaard  <[email protected]>
 
+       * cu.c (intern_cu): Check cuoff points to a real Dwarf_Die before
+       interning.
+
+2015-05-05  Mark Wielaard  <[email protected]>
+
        * dwfl_lineinfo.c (dwfl_lineinfo): Check info->file is valid.
 
 2015-04-21  Mark Wielaard  <[email protected]>
diff --git a/libdwfl/cu.c b/libdwfl/cu.c
index 3ac341e..dbbed85 100644
--- a/libdwfl/cu.c
+++ b/libdwfl/cu.c
@@ -171,6 +171,11 @@ compare_cukey (const void *a, const void *b)
 static Dwfl_Error
 intern_cu (Dwfl_Module *mod, Dwarf_Off cuoff, struct dwfl_cu **result)
 {
+  Dwarf_Die cudie;
+  Dwarf_Die *die = INTUSE(dwarf_offdie) (mod->dw, cuoff, &cudie);
+  if (die == NULL)
+    return DWFL_E_LIBDW;
+
   struct Dwarf_CU dwkey;
   struct dwfl_cu key;
   key.die.cu = &dwkey;
@@ -203,15 +208,7 @@ intern_cu (Dwfl_Module *mod, Dwarf_Off cuoff, struct 
dwfl_cu **result)
          cu->mod = mod;
          cu->next = NULL;
          cu->lines = NULL;
-
-         /* XXX use non-searching lookup */
-         Dwarf_Die *die = INTUSE(dwarf_offdie) (mod->dw, cuoff, &cu->die);
-         if (die == NULL)
-           {
-             free (cu);
-             return DWFL_E_LIBDW;
-           }
-         assert (die == &cu->die);
+         cu->die = cudie;
 
          struct dwfl_cu **newvec = realloc (mod->cu, ((mod->ncu + 1)
                                                       * sizeof (mod->cu[0])));
-- 
2.1.0

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