Zero-initialize linux note sections

This patches changes linux-tdep.c so that the buffer used to write
note sections when generating a core file is zero-initialized.  This
way, bytes that are not collected won't contain random
data (e.g. padding bytes).

gdb/ChangeLog:
2018-10-26  Pedro Franco de Carvalho  <pedromfc@linux.ibm.com>

	* linux-tdep.c (linux_collect_regset_section_cb): Use
	std::vector<gdb_byte> instead of char * and malloc for buf.
	Remove xfree.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 694651bc44ac252047360367b4246515287f5582..411f43f30dc2080453f0f751c680e1b12309fb9d 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,9 @@
+2018-10-26  Pedro Franco de Carvalho  <pedromfc@linux.ibm.com>
+
+       * linux-tdep.c (linux_collect_regset_section_cb): Use
+       std::vector<gdb_byte> instead of char * and malloc for buf.
+       Remove xfree.
+
 2018-10-26  Sangamesh Mallayya <sangamesh.swamy@in.ibm.com>
 
        * xcoffread.c (read_xcoff_symtab): Pass deduced language to

diff --git a/gdb/linux-tdep.c b/gdb/linux-tdep.c
index 352114943fe807d4832a56cf7c1666945c1474c7..c958c0dfe9dbcd2bd10d6e4bcc4ee6def96fd36e 100644 (file)
--- a/gdb/linux-tdep.c
+++ b/gdb/linux-tdep.c
@@ -1584,7 +1584,6 @@ linux_collect_regset_section_cb (const char *sect_name, int supply_size,
                                 int collect_size, const struct regset *regset,
                                 const char *human_name, void *cb_data)
 {
-  char *buf;
   struct linux_collect_regset_section_cb_data *data
     = (struct linux_collect_regset_section_cb_data *) cb_data;
   bool variable_size_section = (regset != NULL
@@ -1598,19 +1597,22 @@ linux_collect_regset_section_cb (const char *sect_name, int supply_size,
 
   gdb_assert (regset && regset->collect_regset);
 
-  buf = (char *) xmalloc (collect_size);
-  regset->collect_regset (regset, data->regcache, -1, buf, collect_size);
+  /* This is intentionally zero-initialized by using std::vector, so
+     that any padding bytes in the core file will show as 0.  */
+  std::vector<gdb_byte> buf (collect_size);
+
+  regset->collect_regset (regset, data->regcache, -1, buf.data (),
+                         collect_size);
 
   /* PRSTATUS still needs to be treated specially.  */
   if (strcmp (sect_name, ".reg") == 0)
     data->note_data = (char *) elfcore_write_prstatus
       (data->obfd, data->note_data, data->note_size, data->lwp,
-       gdb_signal_to_host (data->stop_signal), buf);
+       gdb_signal_to_host (data->stop_signal), buf.data ());
   else
     data->note_data = (char *) elfcore_write_register_note
       (data->obfd, data->note_data, data->note_size,
-       sect_name, buf, collect_size);
-  xfree (buf);
+       sect_name, buf.data (), collect_size);
 
   if (data->note_data == NULL)
     data->abort_iteration = 1;