[binutils-gdb] PR18452, ld allows overlapping sections

[Alan Modra <amodra at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=136a43b762ce7bc692645cc0d9d50c934f9aa392

commit 136a43b762ce7bc692645cc0d9d50c934f9aa392
Author: Alan Modra <amodra@gmail.com>
Date:   Fri Apr 8 17:52:03 2016 +0930

    PR18452, ld allows overlapping sections
    
    	PR 18452
    	* ldlang.c (maybe_overlays): Delete.
    	(lang_size_sections_1): Remove code setting maybe_overlays.
    	(lang_check_section_addresses): Instead detect overlays by
    	exact match of section VMAs here.  Fix memory leak.

Diff:
---
 ld/ChangeLog |  8 ++++++++
 ld/ldlang.c  | 45 ++++++++++++++++++++++++++-------------------
 2 files changed, 34 insertions(+), 19 deletions(-)

diff --git a/ld/ChangeLog b/ld/ChangeLog
index 4d82ea4..3c40941 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,11 @@
+2016-04-08  Alan Modra  <amodra@gmail.com>
+
+	PR 18452
+	* ldlang.c (maybe_overlays): Delete.
+	(lang_size_sections_1): Remove code setting maybe_overlays.
+	(lang_check_section_addresses): Instead detect overlays by
+	exact match of section VMAs here.  Fix memory leak.
+
 2016-04-08  Dan Gisselquist  <dgisselq@ieee.org>
 
 	* ldlang.c (print_output_section_statement): Show minfo size
diff --git a/ld/ldlang.c b/ld/ldlang.c
index 5fbea3f..1947efc 100644
--- a/ld/ldlang.c
+++ b/ld/ldlang.c
@@ -75,7 +75,6 @@ static lang_statement_list_type **stat_save_ptr = &stat_save[0];
 static struct unique_sections *unique_section_list;
 static struct asneeded_minfo *asneeded_list_head;
 static unsigned int opb_shift = 0;
-static bfd_boolean maybe_overlays = FALSE;
 
 /* Forward declarations.  */
 static void exp_init_os (etree_type *);
@@ -4742,6 +4741,7 @@ lang_check_section_addresses (void)
   bfd_vma p_start = 0;
   bfd_vma p_end = 0;
   lang_memory_region_type *m;
+  bfd_boolean overlays;
 
   if (bfd_count_sections (link_info.output_bfd) <= 1)
     return;
@@ -4763,11 +4763,14 @@ lang_check_section_addresses (void)
     }
 
   if (count <= 1)
-    return;
+    {
+      free (sections);
+      return;
+    }
 
   qsort (sections, count, sizeof (*sections), sort_sections_by_lma);
 
-  /* First check sections LMAs.  There should be no overlap of LMAs on
+  /* First check section LMAs.  There should be no overlap of LMAs on
      loadable sections, even with overlays.  */
   for (p = NULL, i = 0; i < count; i++)
     {
@@ -4797,11 +4800,28 @@ lang_check_section_addresses (void)
 	}
     }
 
-  /* Now check sections VMAs if no overlays were detected.  */
-  if (!maybe_overlays)
+  /* If any non-zero size allocated section (excluding tbss) starts at
+     exactly the same VMA as another such section, then we have
+     overlays.  Overlays generated by the OVERLAY keyword will have
+     this property.  It is possible to intentionally generate overlays
+     that fail this test, but it would be unusual.  */
+  qsort (sections, count, sizeof (*sections), sort_sections_by_vma);
+  overlays = FALSE;
+  p_start = sections[0].sec->vma;
+  for (i = 1; i < count; i++)
     {
-      qsort (sections, count, sizeof (*sections), sort_sections_by_vma);
+      s_start = sections[i].sec->vma;
+      if (p_start == s_start)
+	{
+	  overlays = TRUE;
+	  break;
+	}
+      p_start = s_start;
+    }
 
+  /* Now check section VMAs if no overlays were detected.  */
+  if (!overlays)
+    {
       for (p = NULL, i = 0; i < count; i++)
 	{
 	  s = sections[i].sec;
@@ -4835,7 +4855,6 @@ lang_check_section_addresses (void)
     if (m->had_full_message)
       einfo (_("%X%P: region `%s' overflowed by %ld bytes\n"),
 	     m->name_list.name, (long)(m->current - (m->origin + m->length)));
-
 }
 
 /* Make sure the new address is within the region.  We explicitly permit the
@@ -5149,18 +5168,6 @@ lang_size_sections_1
 	    if (bfd_is_abs_section (os->bfd_section) || os->ignored)
 	      break;
 
-	    if (r->last_os != NULL
-		&& !IGNORE_SECTION (os->bfd_section)
-		&& os->bfd_section->size != 0)
-	      {
-		asection *last;
-
-		last = r->last_os->output_section_statement.bfd_section;
-		if (dot + TO_ADDR (os->bfd_section->size) > last->vma
-		    && dot < last->vma + TO_ADDR (last->size))
-		  maybe_overlays = TRUE;
-	      }
-
 	    /* Keep track of normal sections using the default
 	       lma region.  We use this to set the lma for
 	       following sections.  Overlays or other linker