libdw: Don't leak duplicate FDEs.

Although it isn't supposed to happen there could be FDEs that cover the
same address range. Don't leak such FDEs and use an existing FDE for
consistency.

Signed-off-by: Mark Wielaard <mjw@redhat.com>

2 files changed, 14 insertions, 1 deletions

diff --git a/libdw/ChangeLog b/libdw/ChangeLog
index 738e2236..d0e97f3c 100644
--- a/libdw/ChangeLog
+++ b/libdw/ChangeLog
@@ -1,3 +1,7 @@
+2015-12-02  Mark Wielaard  <mjw@redhat.com>
+
+	* fde.c (intern_fde): Don't leak duplicate FDEs.
+
 2015-12-01  Mark Wielaard  <mjw@redhat.com>
 
 	* fde.c (intern_fde): Don't intern an fde that doesn't cover a
diff --git a/libdw/fde.c b/libdw/fde.c
index 2a59d3e1..f5f6fbe1 100644
--- a/libdw/fde.c
+++ b/libdw/fde.c
@@ -119,12 +119,21 @@ intern_fde (Dwarf_CFI *cache, const Dwarf_FDE *entry)
     fde->instructions += cie->fde_augmentation_data_size;
 
   /* Add the new entry to the search tree.  */
-  if (tsearch (fde, &cache->fde_tree, &compare_fde) == NULL)
+  struct dwarf_fde **tres = tsearch (fde, &cache->fde_tree, &compare_fde);
+  if (tres == NULL)
     {
       free (fde);
       __libdw_seterrno (DWARF_E_NOMEM);
       return NULL;
     }
+  else if (*tres != fde)
+    {
+      /* There is already an FDE in the cache that covers the same
+	 address range.  That is odd.  Ignore this FDE.  And just use
+	 the one in the cache for consistency.  */
+      free (fde);
+      return *tres;
+    }
 
   return fde;
 }