Prevent a potential use-after-fee memory corruption bug in the linker (for PE format files).

	PR 25993
	* emultempl/pe.em (_after_open): Check for duplicate filename
	pointers before renaming the dll.
	* emultempl/pep.em (_after_open): Likewise.

3 files changed, 46 insertions, 12 deletions

diff --git a/ld/ChangeLog b/ld/ChangeLog
index 5923e4c..49c6970 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,10 @@
+2020-05-18  Nick Clifton  <nickc@redhat.com>
+
+	PR 25993
+	* emultempl/pe.em (_after_open): Check for duplicate filename
+	pointers before renaming the dll.
+	* emultempl/pep.em (_after_open): Likewise.
+
 2020-05-13  Nick Clifton  <nickc@redhat.com>
 
 	PR 25979
diff --git a/ld/emultempl/pe.em b/ld/emultempl/pe.em
index 4fe195e..ad5d65d 100644
--- a/ld/emultempl/pe.em
+++ b/ld/emultempl/pe.em
@@ -1655,13 +1655,27 @@ gld_${EMULATION_NAME}_after_open (void)
 		else /* sentinel */
 		  seq = 'c';
 
-		new_name = xmalloc (strlen (is->the_bfd->filename) + 3);
-		sprintf (new_name, "%s.%c", is->the_bfd->filename, seq);
-		bfd_set_filename (is->the_bfd, new_name);
 
-		new_name = xmalloc (strlen (is->filename) + 3);
-		sprintf (new_name, "%s.%c", is->filename, seq);
-		is->filename = new_name;
+		/* PR 25993: It is possible that is->the_bfd-filename == is->filename.
+		   In which case calling bfd_set_filename on one will free the memory
+		   pointed to by the other.  */
+		if (is->filename == is->the_bfd->filename)
+		  {
+		    new_name = xmalloc (strlen (is->filename) + 3);
+		    sprintf (new_name, "%s.%c", is->filename, seq);
+		    bfd_set_filename (is->the_bfd, new_name);
+		    is->filename = new_name;
+		  }
+		else
+		  {
+		    new_name = xmalloc (strlen (is->the_bfd->filename) + 3);
+		    sprintf (new_name, "%s.%c", is->the_bfd->filename, seq);
+		    bfd_set_filename (is->the_bfd, new_name);
+
+		    new_name = xmalloc (strlen (is->filename) + 3);
+		    sprintf (new_name, "%s.%c", is->filename, seq);
+		    is->filename = new_name;
+		  }
 	      }
 	  }
       }
diff --git a/ld/emultempl/pep.em b/ld/emultempl/pep.em
index 3e03eb3..aa8bac5 100644
--- a/ld/emultempl/pep.em
+++ b/ld/emultempl/pep.em
@@ -1623,13 +1623,26 @@ gld_${EMULATION_NAME}_after_open (void)
 		else /* sentinel */
 		  seq = 'c';
 
-		new_name = xmalloc (strlen (is->the_bfd->filename) + 3);
-		sprintf (new_name, "%s.%c", is->the_bfd->filename, seq);
-		bfd_set_filename (is->the_bfd, new_name);
+		/* PR 25993: It is possible that is->the_bfd-filename == is->filename.
+		   In which case calling bfd_set_filename on one will free the memory
+		   pointed to by the other.  */
+		if (is->filename == is->the_bfd->filename)
+		  {
+		    new_name = xmalloc (strlen (is->filename) + 3);
+		    sprintf (new_name, "%s.%c", is->filename, seq);
+		    bfd_set_filename (is->the_bfd, new_name);
+		    is->filename = new_name;
+		  }
+		else
+		  {
+		    new_name = xmalloc (strlen (is->the_bfd->filename) + 3);
+		    sprintf (new_name, "%s.%c", is->the_bfd->filename, seq);
+		    bfd_set_filename (is->the_bfd, new_name);
 
-		new_name = xmalloc (strlen (is->filename) + 3);
-		sprintf (new_name, "%s.%c", is->filename, seq);
-		is->filename = new_name;
+		    new_name = xmalloc (strlen (is->filename) + 3);
+		    sprintf (new_name, "%s.%c", is->filename, seq);
+		    is->filename = new_name;
+		  }
 	      }
 	  }
       }