net/colo: Fix a "double free" crash to clear the conn_list

We notice the QEMU may crash when the guest has too many
incoming network connections with the following log:

[email protected]:colo_proxy_main : colo proxy connection hashtable full, clear it
free(): invalid pointer
[1]    15195 abort (core dumped)  qemu-system-x86_64 ....

This is because we create the s->connection_track_table with
g_hash_table_new_full() which is defined as:

GHashTable * g_hash_table_new_full (GHashFunc hash_func,
                       GEqualFunc key_equal_func,
                       GDestroyNotify key_destroy_func,
                       GDestroyNotify value_destroy_func);

The fourth parameter connection_destroy() will be called to free the
memory allocated for all 'Connection' values in the hashtable when
we call g_hash_table_remove_all() in the connection_hashtable_reset().

But both connection_track_table and conn_list reference to the same
conn instance. It will trigger double free in conn_list clear. So this
patch remove free action on hash table side to avoid double free the
conn.

Signed-off-by: Like Xu <[email protected]>
Signed-off-by: Zhang Chen <[email protected]>
Signed-off-by: Jason Wang <[email protected]>

Author: zhangckid

net/colo-compare.c

@@ -1323,7 +1323,7 @@ static void colo_compare_complete(UserCreatable *uc, Error **errp)
     s->connection_track_table = g_hash_table_new_full(connection_key_hash,
                                                       connection_key_equal,
                                                       g_free,
-                                                      connection_destroy);
+                                                      NULL);
 
     colo_compare_iothread(s);
 

net/filter-rewriter.c

@@ -383,7 +383,7 @@ static void colo_rewriter_setup(NetFilterState *nf, Error **errp)
     s->connection_track_table = g_hash_table_new_full(connection_key_hash,
                                                       connection_key_equal,
                                                       g_free,
-                                                      connection_destroy);
+                                                      NULL);
     s->incoming_queue = qemu_new_net_queue(qemu_netfilter_pass_to_next, nf);
 }