[lwip-devel] [patch #9288] Possible null-pointer dereference

[Sergio R. Caprile]

Follow-up Comment #2, patch #9288 (project lwip):

The possible null pointer was already caught by the assertion:

   LWIP_ASSERT("recv_udp must have an argument", arg != NULL);  
   conn = (struct netconn *)arg;
+
+  if (conn == NULL) {
+    pbuf_free(p);
+    return;
+  }
+

conn is arg, and arg is checked for not NULL in the assertion;
so this added piece of code is a redundant check.

Then, the patch correctly removes unnecessary checks within the if's:

-  if ((conn == NULL) || !sys_mbox_valid(&conn->recvmbox) ||
+  if (!sys_mbox_valid(&conn->recvmbox) ||
       ((recv_avail + (int)(p->tot_len)) > conn->recv_bufsize)) {
 #else  /* LWIP_SO_RCVBUF */
-  if ((conn == NULL) || !sys_mbox_valid(&conn->recvmbox)) {
+  if (!sys_mbox_valid(&conn->recvmbox)) {



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