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authorFlorian Weimer <fweimer@redhat.com>2021-02-12 18:22:59 +0100
committerFlorian Weimer <fweimer@redhat.com>2021-02-12 18:34:03 +0100
commitebcf45a16ca981c8515f88db94e757cfc6fe4b35 (patch)
tree2560589b5bb9131ae8fd62f2973e9fc2de99bbcb
parentce4a94b12e9ead1278326857c23b3102ec9c8452 (diff)
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elf: Do not copy vDSO soname when setting up link map
The kernel does not put the vDSO at special addresses, so writev can
write the name directly.  Also remove the incorrect comment about not
setting l_name.

Andy Lutomirski confirmed in
<https://lore.kernel.org/linux-api/442A16C0-AE5A-4A44-B261-FE6F817EAF3C@amacapital.net/>
that this copy is not necessary.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
-rw-r--r--elf/setup-vdso.h17
1 files changed, 5 insertions, 12 deletions
diff --git a/elf/setup-vdso.h b/elf/setup-vdso.h
index ece840df38..86c491e49c 100644
--- a/elf/setup-vdso.h
+++ b/elf/setup-vdso.h
@@ -80,20 +80,13 @@ setup_vdso (struct link_map *main_map __attribute__ ((unused)),
       l->l_local_scope[0]->r_list = &l->l_real;
 
       /* Now that we have the info handy, use the DSO image's soname
-	 so this object can be looked up by name.  Note that we do not
-	 set l_name here.  That field gives the file name of the DSO,
-	 and this DSO is not associated with any file.  */
+	 so this object can be looked up by name.  */
       if (l->l_info[DT_SONAME] != NULL)
 	{
-	  /* Work around a kernel problem.  The kernel cannot handle
-	     addresses in the vsyscall DSO pages in writev() calls.  */
-	  const char *dsoname = ((char *) D_PTR (l, l_info[DT_STRTAB])
-				 + l->l_info[DT_SONAME]->d_un.d_val);
-	  size_t len = strlen (dsoname) + 1;
-	  char *copy = malloc (len);
-	  if (copy == NULL)
-	    _dl_fatal_printf ("out of memory\n");
-	  l->l_libname->name = l->l_name = memcpy (copy, dsoname, len);
+	  char *dsoname = ((char *) D_PTR (l, l_info[DT_STRTAB])
+			   + l->l_info[DT_SONAME]->d_un.d_val);
+	  l->l_libname->name = dsoname;
+	  l->l_name = dsoname;
 	}
 
       /* Add the vDSO to the object list.  */