Commit 0d459e2f authored Mar 28, 2024 by Pablo Neira Ayuso

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: 72034434 ("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>

parent a45e6889

net/netfilter/nf_tables_api.c

+8 −5

Original line number	Diff line number	Diff line
		@@ -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;