Early backport of upstream patch under discussion:

  [PATCH v3] elf: Fix DFS sorting algorithm for LD_TRACE_LOADED_OBJECTS

  with missing libraries (BZ #28868)

  <https://sourceware.org/pipermail/libc-alpha/2022-February/136641.html>

The tests are still being discussed upstream and are not backported

here.

diff --git a/elf/dl-deps.c b/elf/dl-deps.c

index 237d9636c5be780c..9e30c6c3f6c58783 100644

--- a/elf/dl-deps.c

+++ b/elf/dl-deps.c

@@ -489,6 +489,8 @@ _dl_map_object_deps (struct link_map *map,

   for (nlist = 0, runp = known; runp; runp = runp->next)

     {

+      /* _dl_sort_maps ignores l_faked object, so it is save to not considere

+	 them for nlist.  */

       if (__builtin_expect (trace_mode, 0) && runp->map->l_faked)

 	/* This can happen when we trace the loading.  */

 	--map->l_searchlist.r_nlist;

diff --git a/elf/dl-sort-maps.c b/elf/dl-sort-maps.c

index a274ed66cc987735..72f4ff0e6eda3377 100644

--- a/elf/dl-sort-maps.c

+++ b/elf/dl-sort-maps.c

@@ -140,7 +140,9 @@ static void

 dfs_traversal (struct link_map ***rpo, struct link_map *map,

 	       bool *do_reldeps)

 {

-  if (map->l_visited)

+  /* _dl_map_object_deps filter l_faked objects when calculating the

+     number of maps before calling _dl_sort_maps, ignore them as well.  */

+  if (map->l_visited || map->l_faked)

     return;

   map->l_visited = 1;