_dl_map_object_deps: Use struct scratch_buffer [BZ #18023]

The function comment suggests that _dl_map_object_deps cannot use
malloc, but it already allocates the l_initfini array on the heap, so
the additional allocation should be acceptable.

diff --git a/ChangeLog b/ChangeLog
index b14f1cd..1a2a7f8 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,12 @@
 2018-06-27  Florian Weimer  <fweimer@redhat.com>
 
        [BZ #18023]
+       * elf/dl-deps.c (_dl_map_object_deps): Use struct
+       scratch_buffer instead of extend_alloca.
+
+2018-06-27  Florian Weimer  <fweimer@redhat.com>
+
+       [BZ #18023]
        * sysdeps/unix/sysv/linux/gethostid.c (gethostid): Use struct
        scratch_buffer instead of extend_alloca.  Update comments.
 

diff --git a/elf/dl-deps.c b/elf/dl-deps.c
index 20b8e94..9d9b1ba 100644 (file)
--- a/elf/dl-deps.c
+++ b/elf/dl-deps.c
@@ -27,6 +27,7 @@
 #include <unistd.h>
 #include <sys/param.h>
 #include <ldsodefs.h>
+#include <scratch_buffer.h>
 
 #include <dl-dst.h>
 
@@ -181,9 +182,8 @@ _dl_map_object_deps (struct link_map *map,
   /* Pointer to last unique object.  */
   tail = &known[nlist - 1];
 
-  /* No alloca'd space yet.  */
-  struct link_map **needed_space = NULL;
-  size_t needed_space_bytes = 0;
+  struct scratch_buffer needed_space;
+  scratch_buffer_init (&needed_space);
 
   /* Process each element of the search list, loading each of its
      auxiliary objects and immediate dependencies.  Auxiliary objects
@@ -213,13 +213,12 @@ _dl_map_object_deps (struct link_map *map,
       if (l->l_searchlist.r_list == NULL && l->l_initfini == NULL
          && l != map && l->l_ldnum > 0)
        {
-         size_t new_size = l->l_ldnum * sizeof (struct link_map *);
-
-         if (new_size > needed_space_bytes)
-           needed_space
-             = extend_alloca (needed_space, needed_space_bytes, new_size);
-
-         needed = needed_space;
+         /* l->l_ldnum includes space for the terminating NULL.  */
+         if (!scratch_buffer_set_array_size
+             (&needed_space, l->l_ldnum, sizeof (struct link_map *)))
+           _dl_signal_error (ENOMEM, map->l_name, NULL,
+                             N_("cannot allocate dependency buffer"));
+         needed = needed_space.data;
        }
 
       if (l->l_info[DT_NEEDED] || l->l_info[AUXTAG] || l->l_info[FILTERTAG])
@@ -438,8 +437,11 @@ _dl_map_object_deps (struct link_map *map,
          struct link_map **l_initfini = (struct link_map **)
            malloc ((2 * nneeded + 1) * sizeof needed[0]);
          if (l_initfini == NULL)
-           _dl_signal_error (ENOMEM, map->l_name, NULL,
-                             N_("cannot allocate dependency list"));
+           {
+             scratch_buffer_free (&needed_space);
+             _dl_signal_error (ENOMEM, map->l_name, NULL,
+                               N_("cannot allocate dependency list"));
+           }
          l_initfini[0] = l;
          memcpy (&l_initfini[1], needed, nneeded * sizeof needed[0]);
          memcpy (&l_initfini[nneeded + 1], l_initfini,
@@ -457,6 +459,8 @@ _dl_map_object_deps (struct link_map *map,
     }
 
  out:
+  scratch_buffer_free (&needed_space);
+
   if (errno == 0 && errno_saved != 0)
     __set_errno (errno_saved);