libdwfl: Don't install an Elf handle in a Dwfl_Module twice

dwfl_segment_report_module can be called with the same module
name, start and end address twice (probably because of a corrupt
core file). In that case don't override the main.elf handle if
it already exists.

https://sourceware.org/bugzilla/show_bug.cgi?id=28655

Signed-off-by: Mark Wielaard <mark@klomp.org>

2 files changed, 6 insertions, 1 deletions

diff --git a/libdwfl/ChangeLog b/libdwfl/ChangeLog
index 76e0899e..1f593ac9 100644
--- a/libdwfl/ChangeLog
+++ b/libdwfl/ChangeLog
@@ -1,5 +1,10 @@
 2021-12-08  Mark Wielaard  <mark@klomp.org>
 
+        * dwfl_segment_report_module.c (dwfl_segment_report_module): Check
+        Dwfl_Module isn't associated with an Elf before installing it.
+
+2021-12-08  Mark Wielaard  <mark@klomp.org>
+
         * dwfl_segment_report_module.c (dwfl_segment_report_module): Don't
         trust e_shentsize.
 
diff --git a/libdwfl/dwfl_segment_report_module.c b/libdwfl/dwfl_segment_report_module.c
index be0aff76..f4acfe53 100644
--- a/libdwfl/dwfl_segment_report_module.c
+++ b/libdwfl/dwfl_segment_report_module.c
@@ -963,7 +963,7 @@ dwfl_segment_report_module (Dwfl *dwfl, int ndx, const char *name,
         elf->flags |= ELF_F_MALLOCED;
     }
 
-  if (elf != NULL)
+  if (elf != NULL && mod->main.elf == NULL)
     {
       /* Install the file in the module.  */
       mod->main.elf = elf;