netfilter: nf_tables: release mutex after nft_gc_seq_end from abort path

The commit mutex should not be released during the critical section
between nft_gc_seq_begin() and nft_gc_seq_end(), otherwise, async GC
worker could collect expired objects and get the released commit lock
within the same GC sequence.

nf_tables_module_autoload() temporarily releases the mutex to load
module dependencies, then it goes back to replay the transaction again.
Move it at the end of the abort phase after nft_gc_seq_end() is called.

Cc: stable@vger.kernel.org
Fixes: 720344340fb9 ("netfilter: nf_tables: GC transaction race with abort path")
Reported-by: Kuan-Ting Chen <hexrabbit@devco.re>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index ffcd3213c335854c28007d3f1de717444663d41b..0d432d0674e12db6e31fdeb653e17c91d51ec361 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -10651,11 +10651,6 @@ static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action)
                nf_tables_abort_release(trans);
        }
 
-       if (action == NFNL_ABORT_AUTOLOAD)
-               nf_tables_module_autoload(net);
-       else
-               nf_tables_module_autoload_cleanup(net);
-
        return err;
 }
 
@@ -10672,6 +10667,14 @@ static int nf_tables_abort(struct net *net, struct sk_buff *skb,
 
        WARN_ON_ONCE(!list_empty(&nft_net->commit_list));
 
+       /* module autoload needs to happen after GC sequence update because it
+        * temporarily releases and grabs mutex again.
+        */
+       if (action == NFNL_ABORT_AUTOLOAD)
+               nf_tables_module_autoload(net);
+       else
+               nf_tables_module_autoload_cleanup(net);
+
        mutex_unlock(&nft_net->commit_mutex);
 
        return ret;