erl_interface: Fix ei_skip_term

1 files changed, 20 insertions, 8 deletions

diff --git a/lib/erl_interface/src/decode/decode_trace.c b/lib/erl_interface/src/decode/decode_trace.c
index ebaa78e29e..88fb3451ec 100644
--- a/lib/erl_interface/src/decode/decode_trace.c
+++ b/lib/erl_interface/src/decode/decode_trace.c
@@ -22,18 +22,30 @@
 int ei_decode_trace(const char *buf, int *index, erlang_trace *p)
 {
   int arity = 0;
-  int tindex = *index;
-  
-  /* use a temporary index if any function should fail */
+  int tindex = *index; /* use a temporary index if any function should fail */
+  long *p_flags, *p_label, *p_serial, *p_prev;
+  erlang_pid *p_from;
+
+  if (p != NULL) {
+      p_flags = &p->flags;
+      p_label = &p->label;
+      p_serial = &p->serial;
+      p_prev = &p->prev;
+      p_from = &p->from;
+  }
+  else {
+      p_flags = p_label = p_serial = p_prev = NULL;
+      p_from = NULL;
+  }
 
   /* { Flags, Label, Serial, FromPid, Prev } */
   if (ei_decode_tuple_header(buf, &tindex, &arity)
       || (arity != 5)
-      || ei_decode_long(buf, &tindex, &p->flags)
-      || ei_decode_long(buf, &tindex, &p->label)
-      || ei_decode_long(buf, &tindex, &p->serial)
-      || ei_decode_pid( buf, &tindex, &p->from)
-      || ei_decode_long(buf, &tindex, &p->prev)) return -1;
+      || ei_decode_long(buf, &tindex, p_flags)
+      || ei_decode_long(buf, &tindex, p_label)
+      || ei_decode_long(buf, &tindex, p_serial)
+      || ei_decode_pid( buf, &tindex, p_from)
+      || ei_decode_long(buf, &tindex, p_prev)) return -1;
 
   /* index is updated by the functions we called */