[lwip-users] fix assert triggered in tcp_in.c

[Pedro Alves]

Hi all,

I was getting a few assertions in pbuf_free call about the ref count 
being 0.

The following (hand made) patch fixed it.

In tcp_in.c around where it says:

   /* We deallocate the incoming pbuf. If it was buffered by the
      application, the application should have called pbuf_ref() to
      increase the reference counter in the pbuf. If so, the buffer
      isn't actually deallocated by the call to pbuf_free(), only the
      reference count is decreased. */
-    if (inseg.p != NULL) pbuf_free(inseg.p);
+    if (inseg.p != NULL) {
+    pbuf_free(inseg.p);
+      inseg.p = NULL;
+    }


I have been testing it for a few days, and found no problem.

Cheers,
Pedro Alves