Clear padding in outgoing messages

Padding used to not be cleared in this code base, but that has the
downside of valgrind reporting nuisance warnings (which could be fixed
using valgrind's programmatic interface) but also of potentially leaking
information.  The cost of clearing the padding appears to be
insignificant compared to the cost of doing the real work, and so it is
probably best to just clear it.

Signed-off-by: Erik Boasson <eb@ilities.com>

src/core/ddsi/src/ddsi_serdata_default.c

@@ -102,17 +102,13 @@ static void *serdata_default_append (struct ddsi_serdata_default **d, size_t n)
 
 static void *serdata_default_append_aligned (struct ddsi_serdata_default **d, size_t n, size_t a)
 {
-#if CLEAR_PADDING
-  size_t pos0 = st->pos;
-#endif
+  size_t pos0 = (*d)->pos;
   char *p;
   assert (ispowerof2_size (a));
   (*d)->pos = (uint32_t) alignup_size ((*d)->pos, a);
   p = serdata_default_append (d, n);
-#if CLEAR_PADDING
-  if (p && (*d)->pos > pos0)
-    memset ((*d)->data + pos0, 0, (*d)->pos - pos0);
-#endif
+  while (pos0 < (*d)->pos)
+    (*d)->data[pos0++] = 0;
   return p;
 }
 
@@ -512,6 +508,7 @@ static struct ddsi_serdata *serdata_default_from_sample_rawcdr (const struct dds
     return NULL;
   assert (sample->keysize <= 16);
   serdata_default_append_blob (&d, 1, sample->size, sample->blob);
+  serdata_default_append_aligned (&d, 0, 4);
   d->keyhash.m_set = 1;
   d->keyhash.m_iskey = 1;
   if (sample->keysize == 0)

src/core/ddsi/src/q_ddsi_discovery.c

@@ -289,6 +289,7 @@ int spdp_write (struct participant *pp)
   /* Add PrismTech specific version information */
   {
     ps.present |= PP_PRISMTECH_PARTICIPANT_VERSION_INFO;
+    memset (&ps.prismtech_participant_version_info, 0, sizeof (ps.prismtech_participant_version_info));
     ps.prismtech_participant_version_info.version = 0;
     ps.prismtech_participant_version_info.flags =
       NN_PRISMTECH_FL_DDSI2_PARTICIPANT_FLAG |

src/core/ddsi/src/q_plist.c

@@ -158,8 +158,13 @@ static const void *deser_generic_src (const void * __restrict src, size_t *srcof
 
 static void *ser_generic_align4 (char * __restrict p, size_t * __restrict off)
 {
-  *off = align4size (*off);
-  return p + *off;
+  const size_t off1 = align4size (*off);
+  size_t pad = off1 - *off;
+  char *dst = p + *off;
+  *off = off1;
+  while (pad--)
+    *dst++ = 0;
+  return dst;
 }
 
 static dds_return_t deser_uint32 (uint32_t *dst, const struct dd * __restrict dd, size_t * __restrict off)

src/core/ddsi/src/q_xmsg.c

@@ -809,13 +809,10 @@ void *nn_xmsg_addpar (struct nn_xmsg *m, nn_parameterid_t pid, size_t len)
   phdr->parameterid = pid;
   phdr->length = (uint16_t) len4;
   p = (char *) (phdr + 1);
-  if (len4 > len)
-  {
-    /* zero out padding bytes added to satisfy parameter alignment --
-       alternative: zero out, but this way valgrind/purify can tell us
-       where we forgot to initialize something */
-    memset (p + len, 0, len4 - len);
-  }
+  /* zero out padding bytes added to satisfy parameter alignment: this way
+     valgrind can tell us where we forgot to initialize something */
+  while (len < len4)
+    p[len++] = 0;
   return p;
 }