[patch] Fix for PR gdb/10819

[Paul Pluzhnikov]

On Thu, Oct 22, 2009 at 8:33 AM, Paul Pluzhnikov <ppluzhnikov@google.com> wrote:

> I'll just fix the bsearch calls, since A) one of them is known to
> cause a problem and B) I introduced them recently :-(

Here is the revised patch.

The call to bsearch in dwarf2_frame_find_fde is already preceded by
assert of "fde_table->num_entries > 0", so no changes are needed there.

There is one more call to bsearch in solib-osf.c, but that file appears
to not be used anymore. Ok to deleted it?

Thanks,
-- 
Paul Pluzhnikov

2009-10-22  Paul Pluzhnikov  <ppluzhnikov@google.com>

      PR gdb/10819
      * dwarf2-frame.c (find_cie): Don't call bsearch on
      empty cie_table.
      * objfiles.c (find_pc_section): Likewise.
-------------- next part --------------
Index: dwarf2-frame.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2-frame.c,v
retrieving revision 1.100
diff -u -p -u -r1.100 dwarf2-frame.c
--- dwarf2-frame.c	6 Oct 2009 23:27:04 -0000	1.100
+++ dwarf2-frame.c	22 Oct 2009 16:21:17 -0000
@@ -1525,6 +1525,22 @@ find_cie (struct dwarf2_cie_table *cie_t
 {
   struct dwarf2_cie **p_cie;
 
+  if (cie_table->num_entries == 0)
+    {
+      gdb_assert (cie_table->entries == NULL);
+
+      /* The C standard (ISO/IEC 9899:TC2) requires the BASE argument to
+	 bsearch be a valid pointer even when the NMEMB argument is 0.
+
+	 Passing NULL for BASE and 0 for NMEMB is also known to cause
+	 Solaris-8 bsearch to call bsearch_cie_cmp with NULL ELEMENT
+	 (which doesn't expect that and crashes); see PR gdb/10819.
+
+	 Therefore, avoid calling bsearch under these conditions.  */
+
+      return NULL;
+    }
+
   p_cie = bsearch (&cie_pointer, cie_table->entries, cie_table->num_entries,
                    sizeof (cie_table->entries[0]), bsearch_cie_cmp);
   if (p_cie != NULL)
Index: objfiles.c
===================================================================
RCS file: /cvs/src/src/gdb/objfiles.c,v
retrieving revision 1.99
diff -u -p -u -r1.99 objfiles.c
--- objfiles.c	19 Oct 2009 09:51:41 -0000	1.99
+++ objfiles.c	22 Oct 2009 16:21:17 -0000
@@ -1175,6 +1175,11 @@ find_pc_section (CORE_ADDR pc)
       pspace_info->objfiles_changed_p = 0;
     }
 
+  /* See comment in dwarf2-frame.c:find_cie on why this check
+     is necessary.  */
+  if (pspace_info->num_sections == 0)
+    return NULL;
+
   sp = (struct obj_section **) bsearch (&pc,
 					pspace_info->sections,
 					pspace_info->num_sections,